# Peak level of play (Federer, Nadal, Djokovic & Co.)

Discussion in 'Former Pro Player Talk' started by krosero, Jan 5, 2013.

1. ### kikiBanned

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Not to be preposterous...but what does this thread do on this section? should be in the GP´s.

2. ### SpicyCurry1990Hall of Fame

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Hey krosero, great work! After reading through the methodology I agree that this metric is very good for analyzing the separations in playing levels between two players in a match and showcasing who will win, far better than win/ue ratio.

My question though is this, how can you apply this to compare "levels" from different matches?

For example:
Nadal hits 16 winners/isner forced errors to 1 unforced errors
Isner hits 0 winners/nadal forced errors to 32 unforced errors

Nadal's aggressive margin is 15/49 = 30.5%
Isner's aggressive margin is -32/49 = -65%

Clearly this shows us Nadal dominated this match

But lets say Nadal plays Isner again next week
Isner hits 48 winners/nadal forced errors to 24 unforced errors

Isner's aggressive margin is 24/72 = 33%
Nadal's aggressive margin is 0/72 = 0%

Clearly Isner dominated this match

However when you compare the two matches you see a situation where:

Nadal had a 16:1 ratio of winners/forced errors to unforced errors and lost just 1 point in the match be rated at 30.5%!
vs
Isner only had a 2:1 ratio of winners/forced errors to unforced errors and lost 24 points in the match be rated 33%!

Clearly this does penalize a defensive style because Nadal could play at super high levels defensively and get every ball back in play and either hit winners or only draw errors all match from Isner, and have that performance be rated as worse dropping just 1 point, than a match where Isner dictates the match but sprays a good deal of errors playing offensively. Does this make sense?

Another bias in cross comparison that arises is this is also clearly biased vs defensively levels in general. Example Djokovic vs Nadal at AO 12 had amazing defensive levels. Many shots that could have been "winners" in other matches vs other people were retrieved and put back into play often multiple times in the same point! However, if that point ultimately ended with an unforced error (due to a player going for too big of a shot to finally hit through the great defender) does that mean the quality of that rally is lost? No, but that is how it would come out as in the aggressive margin stat because its indistinguishable from a routine cross court forehand being hit out.

Next of course, this is biased against the level of opponent. Just because Federer has a 40% margin vs Roddick does not mean its a higher level than Djokovic getting 35% vs Nadal because Nadal is a higher quality player.

Finally, this is also biased against slow surfaces, you need to normalize all slams against your average computed value across all matches at that slam to get true levels, because lets say the AM average is 12% at Wimb, 7% at the USO, and 5% at the AO, and 2% at the FO. A performance of 22% at the FO should be rated better than one at 30% at Wimby.

1)great idea to see levels within a match

2)Does not translate to level comparison across matches unless amended by other stats in conjunction, such as total points won being averaged with the Aggressive Margin or something. (Which is what this stat was created to do right, compare levels across matches? We already get a sense of levels within matches just from the score line)

3)This is not biased vs defensive players within a match, but is biased for defensive players across matches

4)This is biased for fast surfaces

5)This does not account for levels of opponents

Last edited: Jul 24, 2014
3. ### NatFTalk Tennis Guru

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I think it was established earlier on in the thread that a high AM against an opponent also with a high AM is more impressive than a high AM against an opponent who's AM is low.

4. ### SpicyCurry1990Hall of Fame

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Not necessarily though any situation is possible. The whole metric relies on rewarding offensive tennis over defensive in cross match comparison.

Equally possible results:

Having a low AM vs an opponent having a low AM - either both players played terrible offense and made a lot of bad mistakes or both players played great defense and many would be winners were put back into play.

Having a high AM vs an opponent having a high AM - either both players played terrible defense and a lot of rallies that should have continued ended with weak stroke winners or both players played great offensively and hit a lot of great winning shots.

Having a high AM vs an opponent having a low AM - either you played a great match offensively and terrible match defensively vs an opponent playing a terrible match in both regards or you played a great match offensively and defensively vs an opponent playing a good match in one or even both regards.

5. ### kandamrgamHall of Fame

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Good work Krosero, cant appreciate enough. Few points:

1. The subjectivity in determining what's a forced error and what's unforced is big deal here. To make the subjective part clear, think about it like this: if a player commits a FE its a decent error, while if he commits a UE then its a poor error from his side. Now apply the same distinction to winners. If a player hits a difficult winner (turning defense to offense) shouldn't we call it a good winner? And similarly a put-away winner as mediocre winner? Differentiating a poor error from a decent error is as subjective as differentiating good winner and mediocre winner.

a. Players like Nadal and Djoker would turn most decent FE into UE since their defense is good to reach the ball, hence it skews the result against their opponents.

b. To make matters worse, Wimbledon officials have an extremely lenient view on UE. That makes Wimbledon AMs so different.

If we get the distinction right, good. But it's not going to work that way. Sometimes I think, ok even though we don't have numbers on easy winners and good winners which would have been an asset, why should we disregard what we have, ie, FE and UE? Something is better than nothing right? Other times the whole subjectivity (as in case of Wimbledon matches) leads me to believe the exercise is pointless. I'm in two minds.

2. No metric is going to tell us the quality of the match. There is no substitute for watching. Stats only tell us how the point ended, not how it was won (or rather how the point was constructed). But this is one step closer, better than Winner-UE differential.

I will list a few drawbacks of AM (most of which others have already stated, especially Spicy Curry), but by no means I mean I'm attacking it. Just so that if it helps.. AM is a good step forward.

3. As others have said AM doesn't really help to gauge quality of modern tennis's grueling nature. It rather tells us how good the match was according to the classical definition of better tennis, ie it tells how well the players played aggressively. If we were all to agree that tennis is better won by playing aggressively and not forcing the opponent to play an error, then yes AM is a good measure. First, it's anti-clay. Clay is not won firing winners. Second, that's not the way tennis in general is moving forward very very unfortunately.

That takes me to the important point. AM is a good metric for matches before say, 1985. Previous eras agree with the logic of AM. The more physical the tennis gets the more AM is invalid. We can restrict it for the past?

4. I see that Federer's AMs have improved over the years since his peak years (04-07). Does that mean he is playing better today? Or did I get this wrong?

5. Match where AM is outright wrong

2010 London
Federer - 25.4%

2011 London
Federer - 48.2%

This suggests 2011 Nadal played better, that too against a much better Federer (as far as AM is concerned, not really speaking). Which is very wrong. Nadal played way way better in 2010. Though the Winner-UE differential states otherwise.

6. AM penalizing clay and defensive games

2011 Rome
Djokovic - 11.5%

One of the best matches on clay in recent times. Dont judge by AM, Nadal was really really high level and the match too. Yet CAM (combined AM) is 17%!!

7. Few matches were my AM doesn't go well with my subjective perception.

UO:

2013 - Nadal 22%, Djokovic 13%
2010 - Nadal 23%, Djokovic 16%
2011 - Djokovic 22%, Nadal 13%

AM suggests 2010 was the best, but my subjective memory tells me 2011 and 2013 were better. Cant argue here.

2007 WC
Federer - 33.1%

2008 WC
Federer - 30.3%

Again AM suggests 2007 was better. Personally I think 2008 had better shot making, rallies etc, overall a higher quality match.

8. Matches where AM doesn't reveal "levels" (point 2. basically)

The following two matches are very interesting. They are different yet similar.

2012 AO
Djokovic - 14.4%

This match was not the greatest in terms of shot making but it was the most brutal and for that one reason it was of very very high quality. The match didn't even happen on clay. Yet the CAM is just 25%!!

2005 AO
Safin - 19%
Federer - 20.8%

This was a very attacking match. And overall very high quality. Yet AM is not that really high because of the UEs that resulted out of the aggressive game. I dont think anybody will argue WC 2007 Final was better than AO 2005 Semi.

The interesting aspect of both the matches is that, in 2012 both the players were defending very very well until errors were extracted from opponent (and since its a long match there were a good share of winners as well), but in the 2005 match both players were outright attacking and for this reason UEs went up as well. So two contrasting styles, yet both were high quality matches resulting in somewhat similar UE and Winners count. So not only AM doesn't tell us the quality here, it also doesn't tell us what kind of game is played. One had UEs because of defense, the other because of aggression.

9. Misleading AM because of aces.

2010 WC
Isner - 39.4%
Mahut - 41.9%

In the end it was a serve fest. Since ace is a winner, you know the end result. The highest CAM I have seen for a match - 81%!! Nobody is going to tell this was better than 2012 AO final.

10. Lastly, Can we call it Aggression Margin rather than Aggressive Margin? The margin itself isn't is aggressive, it's the margin of aggression. Aggressive Margin reminds me of Aggressive Pricing, Marketing etc where pricing/marketing etc can be either aggressive, defensive etc.

6. ### kandamrgamHall of Fame

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I would like to see AM calculated differently.

1. Will discount aces.

2. Will introduce a new factor, "r", which is the rally length. The greater the length of rallies, lesser the effect of UE should be on AM. This will help us in assessing matches like AO '12 Final. Like, "r" will be greater for RG than say for example WC matches. It can be roughly measured as "(duration of match) / (total points)".

3. I will also calculate AM based on their entire errors without the distinction FE and UE. Let me call it EM (Error Margin - nothing much, just a stupid name). This helps in comparing dissimilar matches which doesn't have UE calculation anomalies.

Equation:
Code:
```[B]AMa = (Wa - Aa + FEb - UEa/r)/TP[/B]
```
But,
Code:
`Pa = Wa + FEb + UEb`
Hence,
Code:
`[B]AMa = ((Pa - Aa) - (UEb + UEa/r))/TP[/B]`
Where
Code:
```TP = Total Points in the entire match
A = Aces
FE = Forced Errors
UE = Unforced Errors
W = Winners
P = Points won
r = Rally Length```

Similarly for EM

Equation,
Code:
`[B]EMa = (Wa - Aa - Ea/r)/TP[/B]`
But,
Code:
`Pb = Wb + Ea`
Hence,
Code:
`[B]EMa = ((Wa - Aa) - (Pb - Wb)/r)/TP[/B]`
Where
Code:
```TP = Total Points in the entire match
A = Aces
E = Errors (forced + unforced)
W = Winners
P = Points won
r = Rally Length```

AMs and EMs of few matches:

r = 4 (I remember the stat shown on TV during the 2011 match during the 2nd set that the average rally length on Federer's serve is 4 and on Nadal's serve is 8. Seemed too much to me then, quite unreal. Think 4 is reasonable)

2010 London
Federer - 32.7%, 10.6%

2011 London
Federer - 48.2%, 18.8%

2011 Rome, r = 6
Djokovic - 32.1%, 14.1%

r = 5

2010 UO
Djokovic - 28.9%, 8.9%

2011 UO
Djokovic - 34.3%, 11.2%

2013 UO
Djokovic - 29.3%, 9.5% (oddly, favours Nole for his attacking game)

r = 4

2007 WC
Federer - 33.6%, 4.3% (goes to show Roger didn't play well if we exclude his aces)

2008 WC
Federer - 33.7%, 6.8%

2012 AO, r = 6 (this is true, I remember the stat. At one stage average length was eight)
Djokovic - 27.5%, 7%

2005 AO, r = 4
Safin - 26.3%, 4.2%
Federer - 26.4%, 4.5%

2010 WC, r = 3
Isner - 31.5%, 4.8%
Mahut - 34.1%, 6.5%

Not very perfect, but I think does a better job. r factor is reasonably chosen according to the match. EMs not surprisingly helps in cross-comparing dissimilar matches better.

7. ### kroseroLegend

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Great stuff, guys, all intelligent, interesting comments. Right now I'm mid-stream in some other projects so I can't reply in more detail, but when I find time to get into deep statistical analysis again I'll say more. Feel welcome in the meantime to keep making posts; I'll get to them in time.

8. ### Boom-BoomHall of Fame

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Interesting feat. Do we have stats on other matches without UE?

9. ### kroseroLegend

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No not as far as I know.

10. ### NatFTalk Tennis Guru

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Why should we exclude aces? Surely the serve is an important factor in level of play. It's fine to try and evaluate level of play off the ground but for overall levels it seems silly and biased (IMO) to not include aces. If player A and player B have equal numbers according to your formula but B served significantly better. Surely you'd have to agree B was the better player.

I'd be interested in these numbers with r and aces included.

11. ### Aggasirules5Banned

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Great stuff. While you are at it, also discount moonballs to the backhand.

12. ### NatFTalk Tennis Guru

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Is there any particular site that has rally length recorded?

13. ### itoaxelBanned

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Interesting how far apart each of those years are in aggressive % when all 3 were competitive matches.

14. ### abmkTalk Tennis Guru

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Federer vs Murray Wimbledon 2015 semi-final :

107 points won for federer, 11 UEs
91 points won for murray, 17 UEs

total UE count = 28
total points = 198

fed's AM = (107-28)/198 = 39.9%
murray's AM = (91-28/198) = 31.8%

granted wimbledon scorers are generous with their UE counts .......still ...that's some damn fine numbers !

15. ### NatFTalk Tennis Guru

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Sort of what I thought, incredible stats and an impressive level of play - probably his best serving performance. But not his best match ever by any stretch. His performance against Roddick in 2003 is still his best Wimbledon performance IMO.

16. ### kroseroLegend

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Quite possible. AM's for that match were:

Federer - 44.3%
Roddick - 31.7%

Roddick's AM was similar to Murray's, but Federer's was a little higher against Roddick.

Seems very reasonable to me; and going by that logic Federer's performance in '03 was a little higher than yesterday's, at least statistically. I put in that caveat because comparing AM's across such a long time span can be problematic; and there are also match-ups issues, in any comparison, of course.

One point I agree with in the recent discussion is that aces can inflate AM's. Federer's been serving so great recently, that you have to wonder whether his ace counts are inflating his AM's to any degree (possibly the case with his 50 aces in the '09 final).

But in this comparison it's not a factor. Against Roddick in '03 Federer hit 17 aces in 84 service points. Against Murray yesterday it was 20 aces in 91 points. Practically a wash.

What I'd love to know is Federer's unreturned rate for these matches. Surprised I couldn't find that rate for the Roddick match, I assumed that had been charted and posted somewhere. And yesterday's performance has gone down already as one of Federer's career service performances so it would be interesting to see how well it lives up to that description in unreturned % which is really the best stat to look at.

(It's certainly far better than looking at aces alone -- and only aces, of course, would be reflected in AM's).

Very similar matches these wins over Roddick and Murray, now that we mention them. Both straight-setters, similar length, Federer with 11 UE's yesterday, and 12 against Roddick (a full dozen years ago!)

17. ### kroseroLegend

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The r factor is interesting, and it addresses a central problem with UE, namely: a loose error after 2 or 3 shots is not the same as an "unforced " error made after a grueling 40-ball exchange.

The problem is, aces can't be discounted, not by any stretch. The only reason to take out serves entirely like that would be to isolate the rest of the players' games, ie, to compare their groundies/volleys. But the total match performance has to include aces. That's true for many reasons but in this context I would just want to say that aces are the best answer to the grueling-rally problem: if you're facing someone who's a better groundstroker than you, or better at rallying in general, just don't have the rally! Don't get into one. End the point before it's begun. Best, most efficient way to win a tennis point.

I do agree with you that aces can inflate AM's. No doubt about it. But removing the aces is not a solution, for the reasons I mentioned above and, ultimately, because heavy ace-serving is just one of many tennis dynamics, not all of which are perfectly captured by any single statistical model. I'm not sure any model could do justice equally well to every type of match. Some models will reflect/highlight certain aspects better than others. That's just the nature of statistics, I think.

The model you have above is interesting in that introduces rally length as a factor, but something is off, too, because you've got Nadal above Federer in the 2007 Wimbledon final. That would only be justifiable as a comparison of a limited aspect of the match; for example, maybe your model shows that Nadal's game was superior to Federer's apart from service, which I agree with -- but it doesn't reflect the total result, or the final result, however you want to put it.

18. ### abmkTalk Tennis Guru

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AMs for the USO men's semis :

djokovic vs cilic in the US Open semi :

djokovic : 27.4%
cilic : -9.01%

federer vs wawrinka in the US Open semi :

federer : 29.67%
stan : 9.67%

19. ### abmkTalk Tennis Guru

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djokovic's and opponent's AMs in the wimbledon finals he's won :

2011 :
djokovic : 38.42%

2014 :
djokovic: 35.52%
federer: 33.88%

2015 :
djokovic: 33.91%
federer: 30.42%

funnily, djokovic's AMs are in the reverse order of what I thought were his levels of play in those finals : 2015 > 2014 > 2011 ...

20. ### abmkTalk Tennis Guru

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Federer's AMs at AO 2017 :

vs melzer : 22.9%
vs rubin : 23.36%
vs berdych : 35.76%
vs nishikori : 29.17%
vs M. zverev : 42.04% ( due to more of net play )
vs wawrinka : 19.79%

Nadal's AMs at AO 2017 :

vs mayer : 23.03%
vs baghdatis : 16.85%
vs A.zverev : 20.19%
vs monfils : 15.15%
vs raonic : 30.19%
vs dimitrov : 20%
vs federer : 18.68%

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21. ### LimpinhitterG.O.A.T.

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To my recollection, in the early 80's, when wood racquets were still being used by the majority of players, McEnroe had the highest winner to unforce error ratio, but, few players were hitting more winners than unforced errors in a match, much less a season.

22. ### kroseroLegend

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And all the Fedal meetings at AO

2009 final
Federer 19.88%

2012 SF
Federer 11.96%

2014 SF
Federer 5.76%

2017 final
Federer 22.49%

@abmk, what was your take on the court speed this year? I heard some about the court being faster, but I didn't get to see as much of this AO as I would have liked.

23. ### abmkTalk Tennis Guru

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the conditions were faster in general ...courts were a bit faster ( not as much sand as in the previous years ) and they used different balls ( which were lighter and got less fluffed up )

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24. ### -NN-Legend

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This is interesting.

Just to clarify, the intention of this system is to judge peak play in a relative sense.. right?

Comparing an aggregate AM of 60% in 2010 to one of 40% from 2000 or 1990 or 1950 won't tell us much even if it were possible that the matches could've occurred on the same surface with the same technology between same opponents. I know this sounds obvious but I want to clarify that by understanding a very precise intention.

Secondly, does this measure do any more to tell us about peak level of play than a simple percentage count of points (and/or games) won over a tournament or further, a year? It seems more designed to try and gauge very special individual match performances.

Even if a raw points/games won % is inherently less biased (or pins itself down in less of an assumption) than "AGGRESSIVE margin" (have read critiques regarding pitfalls from earlier in the thread) it still doesn't really allow for any particular accurate cross comparison of absolute level. It's a measure best used for judging players against their own peers. I should think that percentage of points/games won would achieve similar goals without having to pander, by design or by accident, to inherent biases... other than the understanding that different conditions will yield different results, most crudely speaking: grass, clay.

I guess, in short, I'm wondering what AM is really trying to accomplish in more precise terms.

25. ### -NN-Legend

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Interestingly, it's possible within a similar enough time period to generally show better play than a rival against the field and yet win at a much slower rate. Ronnie O'Sullivan is blatantly the best player of his generation in snooker on the micro statistical level and yet still hasn't won as many Triple Crown events as Stephen Hendry despite having a winning span that is many years longer.

This might be down to Ronnie being more likely to put in one bad match over the course of a tournament, and it only takes one blip to get you knocked out. It might also be to with Hendry dominating during a much more convenient time, much like Federer didn't have to deal with Nadal or Djokovic during the first years of his dominance. He had a window before J.Higgins, R.O'Sullivan and M.J.Williams could catch up and mature (all younger and the next gen.) and he did a good job of mopping up the "Majors" during that time.

For the record, much of their primes were concurrent and they span a similar enough era in a sport with largely static conditions and not much noise, where making more absolute judgments regarding level of play is actually somewhat feasible.

Maybe Federer leads Nadal from 2008-2012 by average, median and peak AM, but he won less in that timeframe because maybe a lower AM for Nadal produces an equal standard of play to a higher AM from Federer (against their field and in their conditions). I bet that % of points or games won won't lie, though. I don't know, of course. Just something I'm wondering.

Really, I'm only bringing up a further measure that is still less relevant than wins-losses.

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26. ### pc1G.O.A.T.

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Federer had the highest winning percentage for five years consecutive I believe with just over 90% with Djokovic fractionally below 90%.
For Games Won Percentage in their best years Federer and Nadal were in the 61% range and Djokovic also around there. Anything over 60% for Games Won Percentage is amazing. Laver for example in his Grand Slam year of 1969 wasn't at 60% for example.

Guess I would go with Federer.

27. ### -NN-Legend

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Would be good to have a "resistance" or "competition" rating to further dig into the worth of these numbers in more absolute terms (within the "era") which could be achieved by looking into percentages of games and points won by a greater number of players in a season, as well the specific match-ups encountered by the best players during the season. I know that tennis28.com has some basic stats on % of games won at the Slams by the best five players of the year according to the metric.

Is Federer's ~90% better, worse or as good as Djokovic's ~90%. I know that Federer once had a ridiculous streak of winning finals and beating top-10 players, and that Djokovic holds records (?) for most top-10 players defeated in a season. I imagine a lot of this has to do with the specific serve-return game points win-loss ratios.

Last edited: Feb 6, 2017
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28. ### pc1G.O.A.T.

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No doubt that a resistance rating would be very useful. Not sure how to do it. Would a person figure out the average ranking of the players? Would it be based on winning percentage of opponents? I remember Allen Barra did something like that in one of his NFL books using his computer to not only check the competition but who the competition faced.

Last edited: Feb 6, 2017
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29. ### -NN-Legend

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So we'd do the same and check the competition and who the competition faced and grade the competition by percentage of points or games won and see how far above the norm the top players are from say the top-20 and the top-50 and see how reliably players can beat a certain threshold of proficiency without faltering. So, maybe when Federer has to play opponents on hard-courts who win 57% of their games he has a 76% chance of winning over his best 3-year span, and we'd compare that to Djokovic. I'm kind of hazy on this because I'm trying to work it out as I go along but hopefully that makes some sense. We could come to some understandings by looking at the quality of opponent faced by looking at a) their typical form on a surface as expressed by percentage of games won over their best period on that surface and b) form on a surface as expressed by percentage of games won over a more recent period and c) the form displayed for just the tournament in question up to that round.. and somehow weigh these components.

Last edited: Feb 6, 2017
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30. ### NatFTalk Tennis Guru

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@pc1

https://tt.tennis-warehouse.com/ind...tio-of-fedalovic-qf-opponents-onwards.534658/

I have something on this. It's not fully up to date. It also doesn't take into account the ranking of the players beaten by the QF onwards players. A lower ranked player that comes through several seeds and top 10 players will likely have a lower D/R than a top ranked player who goes through a 'normal' draw.

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31. ### -NN-Legend

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I remember this thread. Criminal how underappreciated it was in that part of the forum.. lost in a torrent of crap. Will look again.

32. ### NatFTalk Tennis Guru

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A little while back I started compiling full stats for all slam wins from the big 3. So that includes first serve percentage, serve speeds, winners, errors, forced errors, total points won etc...I did this for every match the slam champion played AND for every match their opponent played. So for example I've captured that same data from all 7 of Roddick's matches at Wimbledon in 2004 and all 6 of Grosjeans etc...

It ended up being a lot of work, I only finished Wimbledon. I did AM's as well.

But yes that thread of mine was underappreciated

33. ### pc1G.O.A.T.

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I didn't even see the thread. Cannot believe I didn't notice it. It's a great thread but it is a thread for stat geeks like me. It may not be for all.

It sounds great. It's similar to my Games Won percentages which I believe may be a truer indicator of Tennis Strength given relatively similar competition.

While I can find the numbers for GW% it is hard to separate the numbers for the past players for the dominance ratio. For example we know 1984 McEnroe had a Games Won Percentage of 65.32 but we cannot know what percentage of his service games did he win and what percentage of his return games did he win. We did know that with that GW% he was 82-3 for the year which is about right.

D/R may actually be more accurate than GW% if I had to guess.

34. ### -NN-Legend

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Ultimately some years are going to produce varying amounts of great performers. Some years might have particularly strong competition where 5 or 6 of the quarterfinalists are playing great ball, but ultimately there can only be one winner. Other years or Slams might be quite weak and only have a couple of strong performers. Some years might have 5 or 6 strong performers but have 1 particularly anomalous super performer who is a rare next level up for the event. In Slams where a player has won it by being unusually brilliant against a draw that yielded many strong performers, the peak would be better proved especially if that player had to dispose of a couple of those strong performers along the way.

Clearly there are some useful candidates to consider here, namely: AM, DR, GW%.

Which is best?

Why?

Find out in the next episode of Dragon Ball Z.

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35. ### NatFTalk Tennis Guru

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When looking at competition GW's unless done at the tournament level don't say too much IMO. It might capture how consistent a player is across a year but form in a particular events doesn't necessarily depend on how someone performed a few months ago on a potentially different surface. Nadal's numbers coming into Wimbledon every year were probably pretty high but as you move into the grass and HC they would drop.

Yeah impossible to get D/R for older players, but still useful for looking at modern players.

Yes a year like 2007 is a good example for me, there weren't that many consistent contenders but you had great runs from Gonzo at the AO, Nalbandian indoors etc...so the overall numbers might not look great but if you look at each event the competition was good. I think any of those metrics are good, using them in conjunction would be interesting - but for me it's most important to get as granular as possible. I have no interest in using career accomplishments to rate competition for a single match. Even looking at the year on a whole can be deceptive as form can change quickly.

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36. ### pc1G.O.A.T.

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@NatF I think D/R is a fabulous stat. I have to use it to see how it works with current players.

37. ### -NN-Legend

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What if we're vigilant though and record GW% as follows: We could come to some understandings by looking at the quality of opponent faced by looking at a) their typical form on a surface as expressed by percentage of games won over their best period on that surface and b) form on a surface as expressed by percentage of games won over a more recent period and c) the form displayed for just the tournament in question up to that round.. and somehow weigh these components.

Overall I think DR could be best because it discriminates the least against big servers??? Unsure.

38. ### -NN-Legend

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I'm wondering if some sort of Performance Efficiency Rating equivalent could be used in tennis, as is used in basketball.

I guess it doesn't work nearly as well because match-ups aren't guaranteed.

39. ### -NN-Legend

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@NatF

Didn't you produce stats on the strength of recent tennis seasons regarding the Slam events, or was that someone else? I remember it compared competition across a span of something like 2003-2014 or so.

"Yeah impossible to get D/R for older players, but still useful for looking at modern players."

That's true. A shame.

40. ### NatFTalk Tennis Guru

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Is there anything in particular you want to test?

The problem with D/R is that

1) It tends to favour players who win a lot on serve
2) It's also not necessarily fair to those players that coast on return because of their confidence in the serve.Player This probably evens out over time.

I don't think 1) is so much of a problem, it's more important to win on serve than return.

See above what I wrote to pc1.

For your main paragraph we could infact come up with our own measurement weighing all those factors. The issue is how do we subjectively weigh each of those 3 metrics?

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41. ### NatFTalk Tennis Guru

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I did a top 10 win/loss comparison for the 90's through to 2014 (thread title is 2004-2014). But nothing else I don't think.

If you find it share it.

42. ### pc1G.O.A.T.

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It's hard to do a PER stat in tennis because I think in tennis there are fewer stats to measure. I think you would have to really have a stat keeper at every match which is very tough because of the amount of players in the ATP. Perhaps there could have % of forehands hit. Winners on forehand and backhand. Serve winners and % etc.

43. ### -NN-Legend

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The problem I'm seeing is that there are inherent biases in all three measures. GW% runs into the same problem as D/R. I don't know if it's more or less fair than D/R to players who win a lot on serve. @Gary Duane talks about how being 90-30 on serve-return is not the same as being 80-40, even though they reach the same total.

Total win/loss records of top 10-20 players and more: 2004- 2014
https://tt.tennis-warehouse.com/ind...-top-10-20-players-and-more-2004-2014.525044/

44. ### pc1G.O.A.T.

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I want to see how it relates to winning percentage first and foremost but how the ratio translates against players of better or lesser D/R ratios.

45. ### pc1G.O.A.T.

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From what I've seen Gary is incorrect.

46. ### NatFTalk Tennis Guru

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https://tt.tennis-warehouse.com/ind...-strongly-predicts-winning-percentage.461224/

A thread on just that. How familiar are you with tennisabstract? I would suggest using that to test it yourself.

Well 90-30 would be 30/10 = 3 and 80/40 = 2 so yes there is a marked difference. I do think the serve is the more important shot than the return so I do think if it leans one way it should be towards the serve. At the end of the day you have control of your serve so it's a better measure of how well you're playing than if an opponent hits an ace or a DF.

47. ### -NN-Legend

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Do you think a player who is brilliant on return and rallies is just as likely to coast in bothering to produce incisive and potent first serves as a great server is likely to coast some return games? Also, do you think a more return heavy style is just as likely to dominate in the biggest matches against the best opponents as one who is serve heavy? I know that in the past you have questioned out of the legends who had a better serve and who had a better return, and that you felt it was quite evenly split. Obviously, there's more to the serve and return game than just the serve and just the return.

Last edited: Feb 6, 2017
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48. ### -NN-Legend

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It's sad that we have to dig up these great threads rather than having a convenient and dedicated subforum for statistics and "studies".

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49. ### pc1G.O.A.T.

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Yes in the D/R ratio it would be changed but I think it's not a problem in GW%. The winning percentages seem close in either case from what I've seen.

50. ### pc1G.O.A.T.

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That's a great question. I have to think about that. Unfortunately I have some important work to do on my most hated day...Monday.

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