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

[krosero]

Originally Posted by World Beater

Perhaps i dont understand AMs well enough, but isnt the AM of a player dependent on the opponent i.e. it is relative only to the opponent to the other side.

I suppose what one can deduce is whether players are performing "well" as compared to how they usually play. The AM can be used as a benchmark in matchups and whether they had a good day relatively speaking to past matches.

But to compare djokovic to federer for example..there is a small difference in AM. Is this because federer's opponents were better? They certainly performed "better" based on AMs, but this is relative to federer of course. As they can only play federer's shots not djokovic's.

Perhaps what we need is a Delta AM - that is the differene between the player and the opponent. That way we can potentially cancel out stylistic differences that would lead aggressive players to have a higher absolute AM than defense oriented players...

This way we have a better feel for the form of the player as compared to the competition.

Ferrer's form was clearly not that great, and he got smashed as predicted by the AMs. His opponents also subjectively were not necessarily tougher than novak's opponents, and they also performed worse that he did as per opponent's AM.

Yes the AM would be dependent to some degree on the opponent. I think that must be true for almost any measurement in tennis; there are very few things that come to mind that don't depend to some degree on your opponent. Aces and double-faults come to mind; but once the ball reaches your opponent's racquet, you will have his shot to deal with (or his error to benefit from), and it's no longer completely in your hands, so to speak.

It's like counting winners and errors (the most common stats): you can definitely hit more winners if you're facing someone clearly inferior to you; it will not be much of a challenge for you to hit winners past him and to keep from making errors yourself.

That's why I like to use the AM's as a benchmark, like you say, in rivalries. If you keep the same two players constant the comparison is less problematic -- and that's especially true if you keep the surface constant, since surface speed has a great effect on AM's.

It becomes more complex if you're comparing the AM's that two players produce, not against each other, but against the field.

If you're asking why Djokovic and Federer produced similar AM's at this Australian Open, then it's definitely a question to ask, whether Federer's opponents were different in some way -- perhaps inherently superior, or inferior -- to Djokovic's opponents. If there's some large difference in the quality of opposition that Fed and Djok faced at this tournament, that would have an impact on the AM's that they produced.

However it's another thing simply to list as many AM's as you can for the top players in their entire careers. They all play the same competition on the same tour, so you would expect that their AM's can be compared fairly.

At that point, though, there are other issues, like style of play. Does style of play have an impact on AM's? Do AM's favor a certain style?

The more I think about that question the more complex the issue seems to be. We've all been working here on the assumption that SV reduces unforced errors and produces high AM's, because if two players are constantly rushing to net against each other, the defender will always be hitting passing shots or making forced errors, not UE's. And it's true that you can find many matches at Wimbledon, in older eras, where two SV players faced each other, coming in behind every serve, and making very few UE's. Hence they have high AM's.

But there's a twist here: at the most basic level, you get a high AM by keeping your unforced errors down. There's a real opportunity in that sense for players like Borg or Nadal, who are masters at keeping their UE's down, to post high AM's. You can force these men into errors, but they will rarely hand you a point for free. And with low UE's, their AM's have to be high.

By the same token, an aggressive net-rushing player facing a great defender will have no choice but to make a lot of UE's: because they have to go for their shots if they're going to win; and in going for their shots they will make plenty of UE's.

So it's not true that merely having an aggressive style will get you high AM's, while the grinders will have low AM's. That really depends on the matchups.

It's true that two net-rushers facing each other tend to crowd out opportunities to make UE's and they will often post extremely high AM's; and two grinders facing each other will have nothing but opportunities to make unforced errors, so in such matches you will often see low AM's.

But an aggressive player facing a grinder is a different story. I don't know that there is any inherent advantage there, as far as AM's go. The aggressor might easily make a ton of UE's errors, and post a low AM; while the defender might easily get a high AM by making almost no errors.

Upthread we had a discussion about Nadal, because he seems to be the archetype of the grinder who hits a low number of winners and makes a low number of errors. I thought that if we looked at his winner/error differentials, we might find low numbers. But I have found the opposite to be true: when he wins his matches Nadal has a better winner/error differential than his opponents even when he's playing a mega-aggressive player. Nadal might make far fewer winners than someone like Verdasco; but he also makes far fewer errors; and if Nadal wins the match he will almost always have a higher winner/error differential than Verdasco. Just because Nadal's numbers of winners and errors are low, does not mean that he ends up with low winner/error differentials: or to put it another way, just because his winners and errors are low does not mean that he can't post a higher Aggressive Margin. An Aggressive Margin is just the margin of your forcing plays as compared to your errors. Your winners and errors might be low but all you have to do is keep your winners ahead of your errors better than the other guy does, and you win the match.

The absolute figures don't matter here. Nadal can post 50 winners while Verdasco posts 100. The only important question is, if Nadal posts 50 winners while making 30 errors (+20), can Verdasco post his 100 winners while making no more than 80 errors? Can Verdasco, in short, keep ahead of his own errors by a margin of +20? If he can't, he will probably lose that match to Nadal. If Verdasco can only keep ahead of his own errors by 10, while Nadal is keeping ahead by 20, then Nadal will come out at the end having won more points: and that almost always means that Nadal will win the match.

The higher Aggressive Margin, mathematically, always goes to the player who wins the most points.

So why should there be an advantage there for either an aggressive style or a defender's style? All you have to do is keep ahead of your own errors better than the other guys does.

If anything -- I'm not pushing this, but if anything -- someone with heavy topspin who is ridiculously good at keeping his errors down will naturally be posting high AM's.

That's why, against expectation, Nadal posted AM's above 40% even at the 2006 Wimbledon. I mean, it's true that Nadal is caricatured as being nothing but a dirtballer with a forehand in his early days; in fact he could do a lot more; but even so, he's the classic archetype of a defender; and even in '06, before the more "aggressive" facets of his game (like his serve, or his volley) had matured, he was posting these ridiculously high AM's. On grass.

How does something like that happen, if in fact the AM method favors aggressive players who are all about hitting winners?

It's a complex issue, and the style question is a valid one, when it comes to AM's. But it's not straightforward at all.

As far as Nadal goes, I think those numbers from the '06 Wimbledon already show that he was better on grass than he is often given credit for. But we would have to regard him as even an even better grasscourter than that, in '06, if we decided that the AM method really does make aggressive players look better: because then Nadal is posting these high AM's despite the method being inherently biased against him.

I don't think we need to go that far, because I don't think it's been shown that the AM method is inherently advantageous to aggressive players.

[krosero]

Originally Posted by abmk

so fed-tsonga was better match quality wise when compared to djoker-stan going by the AMs .....not by a small margin ... question is how much better was it and how much of the difference was caused by djoker's insane defense ?

Some of the issues here I addressed in the last post above. Just would add a few things.

Djoker's defense was insane but he was not necessarily playing to his best level -- which is arguably one reason for Wawrinka getting so close to beating him. The commentators were saying late in the match that he had been missing a good number of FH's when he went for winners. I think they said that when he had a sitter than he dumped into the net, going for a DTL winner. That was on break point; if Novak had converted he would have been serving at 5-3, for the match. It all could have ended a lot sooner.

Now on the other hand, his defense was ridiculous. I'm just saying there could be another side to that: he found himself in a greater number of long rallies, and in such a long match, because at times his offense was failing him.

[abmk]

Originally Posted by krosero

Some of the issues here I addressed in the last post above. Just would add a few things.

Djoker's defense was insane but he was not necessarily playing to his best level -- which is arguably one reason for Wawrinka getting so close to beating him. The commentators were saying late in the match that he had been missing a good number of FH's when he went for winners. I think they said that when he had a sitter than he dumped into the net, going for a DTL winner. That was on break point; if Novak had converted he would have been serving at 5-3, for the match. It all could have ended a lot sooner.

Now on the other hand, his defense was ridiculous. I'm just saying there could be another side to that: he found himself in a greater number of long rallies, and in such a long match, because at times his offense was failing him.

yeah, djoker wasn't at his best ; the very fact that he was missing quite a few shots when he went for it indicates a lower quality ...

rather than defense, I should've mentioned 'returning' ( getting back serves that in many cases would be forced errors of the return ), thus giving more chance for UEs in the rallies ...

one funny thing about a point you mentioned in that post : nadal @ wimbledon 2006, his forehand wasn't that good in the finals, fed's slice made him cough up quite a few errors, OTOH his BH was absolutely on fire and he blasted many winners and forced many errors from federer with it ...

[corners]

[krosero]

^^ Well there's a small margin there for Djokovic, but it does align with the general view that he's top-ranked and a favorite to win.

Someone in another thread said that Ferrer played poorly (without belief), and that's suggested also in his negative AM. Djokovic and Ferrer, with their grinding styles, could be expected to produce low AM's when they meet; but in this case Djokovic's AM is quite high. So Ferrer's playing level does look genuinely low.

[krosero]

Originally Posted by abmk

yeah, djoker wasn't at his best ; the very fact that he was missing quite a few shots when he went for it indicates a lower quality ...

rather than defense, I should've mentioned 'returning' ( getting back serves that in many cases would be forced errors of the return ), thus giving more chance for UEs in the rallies ...

I am still very skeptical that higher quality of returns can produce lower AM's. It's a valid theory but I don't think there's good evidence for it -- and even in theory, a lot of things have to fall exactly into place for better returning to produce lower AM's.

First of all, if someone is producing quality service returns in the sense that he's cutting down on his unforced errors on the return, then that will immediately raise the AM's. So in theory, when we're comparing two matches and saying that one match has low AM's because it featured better returning, we need the better returning NOT to manifest itself as fewer UE's on the return. It can only manifest as better returns on huge serves that are not normally returned. In other words, the player whom we're saying is doing the quality returning cannot be producing better returns on medium/slow serves that are sometimes dropped into the net or driven out (UE's); if the player is being more careful with such serves and putting them back into play, then he's cutting down on the UE's in the match and raising the AM's.

That, already, strikes me as an unusual situation: for a quality returner to manifest his better returning, not on easy serves, but on hard serves. I'm not saying it can't happen: sometimes you do see players who return better when they have pace to work with; but players who tend to dump off-pace serves into the net are not the kind of players we usually think of as quality returners; and Djokovic is certainly not one of those inferior returners.

Another thing that must happen is this: the superior returner gets these tough serves back into play and the resulting rallies end to a significant degree in unforced errors. That again does not strike me as likely, because if a receiver somehow gets his racquet on a humongous serve and drives it back, when the server expected to see a weak return or no return at all, it's very likely that the server will be forced into an error. Djokovic does that countless of times to his opponents (just like Connors used to do).

It's true that Murray sometimes barely gets his racquet on the ball and his return floats softly, and deep, just inside the opposite baseline; and then a long rally ensues which sometimes ends in an UE. But Djokovic's superior returning very often manifests itself as a forcing return that shocks the server or throws him off balance and forces him into an error. And even when the server is not forced into an error and manages to scoop the ball back up, Djokovic at that stage is very often in a position to put away the next ball, or to force an error.

Superior returning off BIG, tough serves CAN end up in unforced errors at the end of the rally but very often it doesn't work that way.

When we tested this theory in the Djokovic/Murray/Fed matches last summer in the last two rounds at Wimbledon, you argued that Murray returned better than Djokovic and put more balls back into play, thus presenting more opportunities for UE's. But you saw my calculations: the number of extra balls that Murray put back in play cannot have resulted in more than 2 or 3 extra UE's, if that.

Additionally, you counted UE's on the return in both matches, and you found Murray making fewer of those errors than Djokovic did. That makes a lot of sense, given Murray's style of returning and style of play in general. But if that's the case -- if Murray returned better than Djokovic in those matches and the quality of Murray's returns manifested as fewer UE's -- then that just about the settles the question in my mind. Murray's superior returning, in the final, was REDUCING the number of UE's in that match, and raising the AM's. So if the final has lower AM's than the semifinal between Fed/Djokovic, we need to find some cause other than Murray's superior returning.

[corners]

Brignacca gives us the following data from the 2005 Australian Open: In 127 matches charted, the average match winner AM was 22.5% and the average loser's AM was 11.0%.

I've only charted the AMs for the top 10 seeds plus a couple of potential spoilers (Raonic, Tomic) and Chardy, who made a run to the quarters. (I'm leaving out Monfils, as he's the outlier of outliers.) Here are the average AMs for the winners of all matches in the table and the average AMs of all losers of those matches:

Average AM of match winners: 23.2%

Average AM of match losers: 8.5%

So the these are pretty close to the 2005 averages. Since the wins were all posted by top 10 players or future top-10 players (Tomic & Raonic), we would expect the winning average to be greater than the whole-tournament winner's average from 2005, since that figure included many more early round victories posted by lower ranked players. The losses were distributed through the full seven rounds, but included the losses of 11 of the 12 quality players here under consideration (excluding the champion of course), so we might have expected the loser's average to be a bit higher as a consequence. I would generally expect the seeds to go down with a fight and post higher-than-average AMs in defeat. But this was not the case at this tournament: only 6 of the 12 (Federer, Tsonga, DelPotro, Gasquet, Raonic and Tomic) posted AMs greater than 10.0 in defeat. Interestingly, 4 of those men lost to Federer, which would seem to support the widespread pre-tournament view that he had a tough draw.

There was some talk at this tournament that the surface played faster this year than in previous years. I would say that the average AMs here do not support this view. On the other hand, many of these matches were played at night, when the courts apparently play much slower, so that may have skewed the AMs, but I'm not going to bother trying to sort that out.

[hoodjem]

Originally Posted by corners

It looks like this chart predicts that Djokovic will win in the finals, by about 8%.

Interesting.

[corners]

Originally Posted by hoodjem

It looks like this chart predicts that Djokovic will win in the finals, by about 8%.

Interesting.

Yeah, based on this small sampling of data, it would appear that AMs might be useful as a predictor of victory in the later rounds of a tournament. Of course, a player could always bring out their best form after struggling through early rounds and blow the whole thing up, but that kind of thing can't be predicted by any other contrivance or art that I'm aware of.

[krosero]

2011 AO
Djokovic - 14.1%
Murray - (1.1%) (neg.)

2012 AO
Djokovic - 8.4%
Murray - 1.7%

2013 AO
Djokovic - 12.1%
Murray - 7.8%

2012 USO
Murray - 12.4%
Djokovic - 10.8%

2012 Shanghai
Djokovic - 14.2%
Murray - 11.6%

2012 London Olympics
Murray - 34.2%
Djokovic - 27.6%

[krosero]

Here's a piece at Straight Sets about the poor returning in the men's final: http://straightsets.blogs.nytimes.co...eturn-success/.

Murray thought it had to do with the surface being faster this year (the AM's I just posted for Djok/Murray matches do suggest that the court played faster this year).

[krosero]

2007 AO
Federer - 25.4%
Djokovic - 9.4%

2008 AO
Djokovic - 24.3%
Federer - 18.0%

2011 AO
Djokovic - 17.4%
Federer - 13.9%

In 2008 they made the switch from Rebound Ace to Plexicushion. I am not sure but I have heard that Plexicushion is slower.

The AM's in '11 are lower than in '08, which is one piece of evidence that the Plexicushion itself was slowed down during the intervening years.

[Bursztyn]

Originally Posted by krosero

I think I have to go back to what I said in one of the earlier posts (I forget which one). If a player increases his level of play, it's hard to imagine him not cutting down on his UE's.

With the other kinds of points -- the winners and forced errors -- there's a kind of logic to arguing that the defender, by raising his level, will offset the more successfully aggressive play of his opponent. You give as good as you get.

Not saying I agree that that could happen, but I see where you're coming from.

With the UE's, though, it's different. Those are the kind of errors that have least to do with what your opponent is doing. Those are the kind that you make when your concentration breaks momentarily; or you get physically lazy or something; or you've got a relatively simple shot but because you have a slight flaw in your technique you miss it.

I think we all agree that there are different kinds of UE's, and that sometimes an error is marked down as unforced even when the player commits it after a long, exhausting rally. On those points you could say that your opponent has a lot to do with your error.

But let's leave those ambiguous points aside. I'm talking about the most basic errors in a match: the ones that are entirely due to yourself. Every match has those. No one can play a perfect match.

And if the two players have genuinely raised their level, I can't see how they would not cut down on those types of errors.

I would expect those types of errors to decrease first and foremost, when you're playing well.

Anyway, once the UE's decrease, the AM's increase.

Still can't see how increased level of play can fail to raise AM's -- though it's still an interesting question!

The scenario that I proposed seems to be logical (if the conditions outlined are fulfilled, the level of play may increase without changing the AM values of both players).

Is this scenario very realistic? I don't think so, however I do not find it completely unrealistic either.

As you have already mentioned sometimes quality rallies may end in an unforced error, although usually the number of UEs is reduced when the quality of play goes up. So the quality of play is in some way reflected by the AM's, however this relationship isn't straighforward. Actual values of the AM's are also shaped by these hypothetical situations (involving winners, forced errors and unforced errors) that I outlined in my scenario.

Perhaps the AM's are match-up sensitive? If this is the case the AM's may provide a convenient tool to compare matches played by the same opponents on the same or similar surface.

[corners]

Originally Posted by krosero

In 2008 they made the switch from Rebound Ace to Plexicushion. I am not sure but I have heard that Plexicushion is slower.

The AM's in '11 are lower than in '08, which is one piece of evidence that the Plexicushion itself was slowed down during the intervening years.

It's difficult to figure out exactly what court surface they are using and what speed it is. The companies that make Rebound Ace and Plexicusion each make several different products of various speeds that each carry the Rebound Ace or Plexicusion branding. From the ITF court pace classification page:

Category 2, Medium-Slow:

Plexipave IW Acrylic

Category 3, Medium:

Rebound Ace GS 8mm
Rebound Ace Pro International Medium

Category 4, Medium-Fast:

Plexicushion Prestige
Plexicushion Prestige AUS
Plexipave
Rebound Ace HSA Club
Rebound Ace Pro International
Rebound Ace Synpave

"Plexipave" refers to the acrylic surface itself while "Plexicushion" refers to the EPDM rubber sub-surface. Here are the three Plexipave top surfaces marketed by the company, from their website:

Plexipave IW - ITF Category 1 - Pace: Slow
For those who desire a much slower surface, to compensate for lower humidity, high altitudes or simply to change the pace of the game, Plexipave has developed the I.W. mixture, first used at the Indian Wells, CA tournament facility.

Plexipave Standard - ITF Category 3 - Pace: Medium
Considered by many to be the best combination of consistency-of-play, pace and foothing. Plexipave Standard is the traditional and most widely used tennis court surface system. Standard Plexipave provides a consistent and reliable medium-pace playing surface.

Plexipave H.U. - ITF Category 4 - Pace: Medium-Fast
Harvard University has been the birthplace of many great innovations and playing traditions. Plexipave H.U. is no exception. It has also been adapted as the standard for the Australian Open Series.

So according to Plexipave, Plexipave H.U. has been adopted as the standard for the Australian Open series.

On the Plexicushion page "PLEXICUSHION PRESTIGE - SURFACE OF THE AUSTRALIAN OPEN"

So according to Plexipave, the AO surface is a Plexipave H.U. acrylic topcoat over a Plexicushion Prestige subsurface. Both of these products are classified by ITF as "Medium-Fast" surfaces. The press, however, has consistently described the surface at the AO as "Medium". In short, there is no way of knowing if the courts are faster or slower from one year to the next without somebody in the know doing the telling.

[Moose Malloy]

For each year, for Murray’s first six matches, I compared his aggressiveness with that of his opponents in two ways. To check how successful he was at hitting big shots compared to his opponents, I added up his winners and his opponents’ forced errors — mistakes they made as a result of Murray shots — and compared those with the sum of his opponents’ winners and his forced errors. Then, I compared Murray’s unforced errors with his opponents’; if he was playing more aggressively, he should also be ending more of the points he loses with his own racket than his opponents, or at least more than he used to.

The stats suggest that not much has changed. In 2011, Murray won 21.3% more points with his racket than his opponents did in his first six matches. That dipped to 20% last year, and rose to 22.5% this year — slight blips, but not a significant shift. Meanwhile, the unforced-errors stats suggest he hasn’t gotten much more willing to accept risk. In 2011, he hit 36% fewer unforced errors in his first six matches than his opponents did. Last year, that figure fell to 21.4% — Murray was losing more points with his aggression than he used to, though still fewer than his opponents did. But this year Murray has lost 34.1% fewer points to unforced errors than his opponents have, indicating he is again winning lots of points by playing less risky tennis than his opponents.

http://blogs.wsj.com/dailyfix/2013/0...ke-old-murray/

[abmk]

Originally Posted by corners

Thanks. I'll have to go back and watch that one. Haven't seen it in over six years

Do you think it was immediately after that match that Toni and Rafa resolved to attack the slice mercilessly? Nowadays, Rafa seems utterly committed to attacking the slice with the forehand whenever he sees it, and with the spin he can produce he can rip the short slice up over the net and into a corner like no one else. He's nearly eliminated that shot from Roger's arsenal when they play, further torturing Fed's backhand side. I also remember reading a piece by Steve Tignor in which he relates walking by a practice court at Indian Wells and seeing Rafa ripping backhands off short slices too (this was maybe 3-4 years ago). The domination of your backhand is now complete, no?

heh, not really sure ..... people talk about the rafa FH high up to fed's BH all the time, but rafa just ripping apart those slices unless they are absolute top notch is just as important factor ...

[corners]

Originally Posted by abmk

heh, not really sure ..... people talk about the rafa FH high up to fed's BH all the time, but rafa just ripping apart those slices unless they are absolute top notch is just as important factor ...

Yeah, I agree. Hit him the ball he most doesn't want to see over and over again and take away as many of the shots he would like to hit - an approach Mr. Tilden would have hurrahed.

[abmk]

Originally Posted by krosero

I am still very skeptical that higher quality of returns can produce lower AM's. It's a valid theory but I don't think there's good evidence for it -- and even in theory, a lot of things have to fall exactly into place for better returning to produce lower AM's.

First of all, if someone is producing quality service returns in the sense that he's cutting down on his unforced errors on the return, then that will immediately raise the AM's. So in theory, when we're comparing two matches and saying that one match has low AM's because it featured better returning, we need the better returning NOT to manifest itself as fewer UE's on the return. It can only manifest as better returns on huge serves that are not normally returned. In other words, the player whom we're saying is doing the quality returning cannot be producing better returns on medium/slow serves that are sometimes dropped into the net or driven out (UE's); if the player is being more careful with such serves and putting them back into play, then he's cutting down on the UE's in the match and raising the AM's.

That, already, strikes me as an unusual situation: for a quality returner to manifest his better returning, not on easy serves, but on hard serves. I'm not saying it can't happen: sometimes you do see players who return better when they have pace to work with; but players who tend to dump off-pace serves into the net are not the kind of players we usually think of as quality returners; and Djokovic is certainly not one of those inferior returners.

Another thing that must happen is this: the superior returner gets these tough serves back into play and the resulting rallies end to a significant degree in unforced errors. That again does not strike me as likely, because if a receiver somehow gets his racquet on a humongous serve and drives it back, when the server expected to see a weak return or no return at all, it's very likely that the server will be forced into an error. Djokovic does that countless of times to his opponents (just like Connors used to do).

It's true that Murray sometimes barely gets his racquet on the ball and his return floats softly, and deep, just inside the opposite baseline; and then a long rally ensues which sometimes ends in an UE. But Djokovic's superior returning very often manifests itself as a forcing return that shocks the server or throws him off balance and forces him into an error. And even when the server is not forced into an error and manages to scoop the ball back up, Djokovic at that stage is very often in a position to put away the next ball, or to force an error.

Superior returning off BIG, tough serves CAN end up in unforced errors at the end of the rally but very often it doesn't work that way.

When we tested this theory in the Djokovic/Murray/Fed matches last summer in the last two rounds at Wimbledon, you argued that Murray returned better than Djokovic and put more balls back into play, thus presenting more opportunities for UE's. But you saw my calculations: the number of extra balls that Murray put back in play cannot have resulted in more than 2 or 3 extra UE's, if that.

Additionally, you counted UE's on the return in both matches, and you found Murray making fewer of those errors than Djokovic did. That makes a lot of sense, given Murray's style of returning and style of play in general. But if that's the case -- if Murray returned better than Djokovic in those matches and the quality of Murray's returns manifested as fewer UE's -- then that just about the settles the question in my mind. Murray's superior returning, in the final, was REDUCING the number of UE's in that match, and raising the AM's. So if the final has lower AM's than the semifinal between Fed/Djokovic, we need to find some cause other than Murray's superior returning.

actually , by my stats

32 UEs in 133 rallies in the semi (24.06%)
49 UEs in 206 rallies in the final (23.8%)

referring back to your post :
http://tt.tennis-warehouse.com/showp...&postcount=130

if we make murray's return % to 56, it comes to 72 returned serves out of 128 rather than the actual 99 out of 128 ... so difference is 27 serves , not 17 serves ...

if we make 20-21 accounting for fed's superior serving in the semis...... no of UEs produced by getting more returns into play ~ 5

earlier calculations for AMs:

http://tt.tennis-warehouse.com/showpost.php?p=7130402&postcount=147

semis :

federer : 31.95%
djokovic : 26.4%

finals :

federer's AM = 29.5%
murray's AM = 24.7%


if we 'remove' these 5 UEs

federer's AM = 31.25%
murray's AM = 26.4%

that brings the AMs in these matches very close ...

having said that murray's superior returning on the first serves doesn't seem to have as much of an effect on the no of UEs as I initially thought ....

perhaps better returning of 1st serves has more of an effect on slower surfaces where % of UEs per no of baseline rallies is more !?

[krosero]

Originally Posted by abmk

actually , by my stats

32 UEs in 133 rallies in the semi (24.06%)
49 UEs in 206 rallies in the final (23.8%)

referring back to your post :
http://tt.tennis-warehouse.com/showp...&postcount=130

if we make murray's return % to 56, it comes to 72 returned serves out of 128 rather than the actual 99 out of 128 ... so difference is 27 serves , not 17 serves ...

if we make 20-21 accounting for fed's superior serving in the semis...... no of UEs produced by getting more returns into play ~ 5

earlier calculations for AMs:

http://tt.tennis-warehouse.com/showpost.php?p=7130402&postcount=147

semis :

federer : 31.95%
djokovic : 26.4%

finals :

federer's AM = 29.5%
murray's AM = 24.7%


if we 'remove' these 5 UEs

federer's AM = 31.25%
murray's AM = 26.4%

that brings the AMs in these matches very close ...

having said that murray's superior returning on the first serves doesn't seem to have as much of an effect on the no of UEs as I initially thought ....

perhaps better returning of 1st serves has more of an effect on slower surfaces where % of UEs per no of baseline rallies is more !?

Yes, since you gave more UE's to the semifinal than Wimbledon.com did, your AM's for the two matches are already very close. And the AM's would be even closer in the hypothetical scenario in which Murray returns only as well as Djokovic did, and we drop 5 UE's from the final -- but I think there are a few problems with that last step.

In your stats Murray made 4 fewer UE's on the return than Djokovic did. And if we're asking how many of the total UE's in the match resulted from Murray's superiority over Djokovic as a returner, those 4 fewer UE's have to be accounted for.

So if Murray's extra returns in play added 5 UE's to the final, his returning also took away 4 UE's. For all intents and purposes that cancels out any effect on the AM's, as far as Murray's extra returns go.

And the UE's that Murray avoided making on 4 points, at least in your count, are certain; the 5 UE's that he added over the course of the match by getting extra returns in play are hypothetical. Most of those extra returns would have been on serves that normally caused forced errors, rather than UE's (that has to be true because the vast majority of the return errors in the match, by anyone's count, were forced).

So I go back to the arguments I made above. If the receiver gets a tough, forcing serve back into play, a common result is for the server to be shocked or thrown off balance, and forced into an error. We're extrapolating our UE's based on the total % of rallies that ended in UE's, but a rally that starts with a tough serve unexpectedly returned is not a typical rally. The % of such rallies that end in UE's could be very different from the overall %.

So the 'extra' UE's produced by Murray's returning could be 5, or perhaps only 2 or 3. And Murray avoided making UE's himself on 4 returns: so I think even going with your numbers it's a very difficult argument to make, that better returning can produce lower AM's.

As far as slower surfaces, as you say, the % of UE in rallies is larger. So hypothetically a receiver who gets a lot of tough first serves back into play can end up inflating the total number of UE's in the match.

However, the same objection there: on slow surfaces, serves do not force errors the way they do on fast surfaces. And the players themselves don't necessarily serve all-out the way they do on fast surfaces. There are more opportunities to make UE's on the return. So a player who displays superior returning skills should also be reducing the UE's in a match when he gets easy/moderate serves back into play, thus raising the AM's.

[krosero]

Nadal against two different opponents at AO.


2009
Nadal - 40.6%
Haas - 18.1%

2012
Nadal - 23.6%
Haas - 13.2%



2009
Nadal - 30.9%
Gonzalez - 12.4%

2007
Gonzalez - 32.1%
Nadal - 22.2%
(this was the year Gonzalez was ripping thru the tournament and posted 45.7% against Haas in the semis)