DATA prove that Wimbledon 2017 is the slowest Wimbledon ever

[Lleytonstation]

All true, but there is also a huge problem. If you have very clear data on one factor but another more important one is not mentioned then your conclusions will be shaky. It really does not good to know "speed" if you don't know "bounce", and the physics behind how all this works is very complicated. You can say accurately what a ball does when it is given a predictable speed, angle, beginning height and X amount of spin. But we should also be interested in how all this changes as these variables change. It's sort of like when they say that player A or B uses more or less topspin, but that doesn't tell us about variety. In yesterday's Fed match he hit a topspin forehand that had so much top on it that a ball that obviously seemed to be going out dropped in right on the line, and it also had side spin bringing it in. If a player hits a lot of top but also flatter balls, which balls are you going to use for a measurement?

If you are looking at the speed of 1st serves, what about off pace slice serves to the deuce court his short in the box? Fed will hit one of those only about 100 mph, and it breaks so far to the right that often players can't even get a racket on it.

As I keep trying to point out, pretty much unsuccessfully, the important factor on grass is not the speed at which the ball takes off after hitting the court but the overall path. Players are so confounded by what the spin does that combined with the low bounce they can look like amateurs at times (an illusion) because the ball does such strange things. Fed hit a nasty looping slice to Berretini that checked so much that Mateo tried to lunge forward and fell down without ever touching the ball. I don't recall ever seeing that happen on clay because the bounce is so high. When you look at the index of speed you're going to think that the AO plays faster. But it doesn't. It doesn't because the higher bounce and truer bounce gives players so much more time to react.

Once again, this is why you need more stats like rally stats as those shots provide more bounces (more interaction with the surface) and more variety of angle, spins, power, and various parts of the court.

 

[Gary Duane]

Once again, this is why you need more stats like rally stats as those shots provide more bounces (more interaction with the surface) and more variety of angle, spins, power, and various parts of the court.

The biggest problem I see is that when most people set up tests they have assumptions about what they are testing. I've thought a lot about how the grass changes. The assumption is that it turns almost into clay, and that is based on what happens at the baseline and at the T. But most people don't think about how often shots are not hit that deep. Think for example about Fed's short slices, which most often are towards the sidelines. That grass is still pretty green and so such shorts will remain very effective. But the wearing of the grass also makes the bounce more and more different from one place in the court to another, and that makes longer swings a problem for obvious reasons. There are so many factors that are not considered in this speed index. On HCs, in contrast, you're dealing with a very uniform bounce, so once you know how high the ball bounces and have a reading on the grit, you know more.

 

[tudwell]

That’s easy. Because eyewitness testimony is notoriously unreliable and contradictional, even if everyone subjectively tries to tell nothing but the truth. For the same reason it is the proof of the lowermost value in any serious court. Any kind of material or documential evidence is ranked higher, even if all witnesses tell the opposite. The exception are political show trials where everything can be "proved" by (alleged) eyewitnesses alone.

The same here: On one hand we have explicit data. On the other hand players tell a feeling or an opinion about the court speed. One says so, the other one the opposite. One could be right, one could have deceived himself, one could even have an agenda to lie about court speed. So whom should we trust? Of course we trust the data.

Also (just as a side note), how should it even be possible to play on the grass right now and then exactly know how it felt in the past years in comparison, after so much other surface changes in between?

I agree with your thoughts on subjective witness testimony (and we can throw in the social factor as well - once one player says it’s slower, that influences other players’ perceptions of the court; it’s not a controlled study or anything), but framing it as “on the one hand” vs. “on the other” isn’t quite accurate either since most of the data supports the conclusion that this is a slower than normal Wimbledon. Even the OP has the lowest average rating between the two singles draws (and the men and women aren’t playing on different courts, so the extra data, if anything, will only help smooth out outliers on the men’s side).

 

[mightyrick]

A measurement such as Court Pace Index means nothing if the empirical observation of professional players and specialists disagree with the result.

In Federer's latest press conference (the Berretini match), railed against the surface again. He talked about how a guy who serves 130+ almost all the time, and keeps the ball in court, should get rewarded a lot more. Federer remarked how he only had like 4 aces? Federer would not credit himself for amazing returning. He simply observed that the slower surface is making those serves easier to return. More so than in past years.

When grass specialists and people who have been successful and played at this venue for many years say it is slower, I simply believe them. They are the experts.

 

[Daniel Andrade]

While we have to look closer to the data, I agree Wimbledon 2017 appears to be as slow as this years Wimbledon and obviously, Federer being the great player he is, he can obviously still win in this one and slower surfaces.

But, I don't quite agree with the title, is W 2017, THE SLOWEST EVER?

I don't think so, perhaps, 2017 and 2019 are the slowest in the last 30 or 20 years...

 

[Daniel Andrade]

it is not measured by the speed of the ball before the bounce vs after the bounce

How do we get those statistics?

 

[Daniel Andrade]

I think that's true, but it is also unintentionally. It is actually that slow due to the weather... It has been a pretty weird summer so far, you know, because of global warming

Lol, I never thought about this.

 

[Daniel Andrade]

A measurement such as Court Pace Index means nothing if the empirical observation of professional players and specialists disagree with the result.

.

That's a simple way of saying that in the hypothetical case that data and more data appears indicating that they're wrong somehow, you simply stick agreeing with your idols.

 

[Daniel Andrade]

Service games won:

'90s - 75.69%
'00s - 77.36%
'10s - 78.75%

Serving is already at its highest influence ever. Some fans want to kill tennis with even faster conditions just to help their favourite player.

That's another thing.

People are winning more points on serve BUT at the same time rallies last 2 points longer.
How's this even possible?
The racquets?

 

[Lew II]

That's another thing.

People are winning more points on serve BUT at the same time rallies last 2 points longer.
How's this even possible?
The racquets?

Maybe that's because players are taller and more athletic. Therefore they both serve and move better, the returner reaches more balls but he eventually loses most of points.

 

[augustobt]

Just when you thought those nonsensical imbecile "data-based" threads were over...

 

[Lleytonstation]

Maybe that's because players are taller and more athletic. Therefore they both serve and move better, the returner reaches more balls but he eventually loses most of points.

I assume the server is still in control of the point even if the return (used to be an ace) comes back.

 

[tudwell]

Maybe that's because players are taller and more athletic. Therefore they both serve and move better, the returner reaches more balls but he eventually loses most of points.

And poly strings. Returners can get more spin on the ball to dip it low if the server tries to come in, so the percentage play now is actually to stand back. It’s safer to hit a couple shots from the baseline than to try to knock off a return up at net. So as poly has allowed greater serve dominance overall it’s also extended points by essentially eliminating S&V as a go-to tactic for top players.

 

[tudwell]

While we have to look closer to the data, I agree Wimbledon 2017 appears to be as slow as this years Wimbledon and obviously, Federer being the great player he is, he can obviously still win in this one and slower surfaces.

But, I don't quite agree with the title, is W 2017, THE SLOWEST EVER?

I don't think so, perhaps, 2017 and 2019 are the slowest in the last 30 or 20 years...

What’s strange is the polar opposite styles of play dominating in 2017 vs. 2019. 5 of the 8 quarterfinalists in 17 were 6’5”+ big-serving players - and 3 of 4 semifinalists. Now Querrey’s the only tall guy to make the quarters. For a tournament with such a low relative ace percentage, 2017 sure had a lot of serve domination. Strange.

 

[Lleytonstation]

What’s strange is the polar opposite styles of play dominating in 2017 vs. 2019. 5 of the 8 quarterfinalists in 17 were 6’5”+ big-serving players - and 3 of 4 semifinalists. Now Querrey’s the only tall guy to make the quarters. For a tournament with such a low relative ace percentage, 2017 sure had a lot of serve domination. Strange.

Cause rallies show court speed more accurately, not serves.

 

[tudwell]

Cause rallies show court speed more accurately, not serves.

I agree but even so, 2017 had some of the fewest aces (relative to the tour average, if I’m reading the OP’s stats right) of any recent Wimbledon, yet big servers still dominated. You’d think those two things would correspond a little more. And here we have another low-ace Wimbledon this year and guys 6’0” or under make up half the quarterfinalists.

 

[Lleytonstation]

I agree but even so, 2017 had some of the fewest aces (relative to the tour average, if I’m reading the OP’s stats right) of any recent Wimbledon, yet big servers still dominated. You’d think those two things would correspond a little more. And here we have another low-ace Wimbledon this year and guys 6’0” or under make up half the quarterfinalists.

Well 2019 is not over and I think when said and done will prove to be much slower overall. Maybe the serves were not aces but still put the returner on defense and the server was able to control the point much easier (as once in a rally they could still outpower smaller guys).

In this slam maybe the returns are not as defensive and taking control is much harder for the big guys. But a lot more attention to detail would have to take place for us to know if this is true or not.

 

[tudwell]

Well 2019 is not over and I think when said and done will prove to be much slower overall. Maybe the serves were not aces but still put the returner on defense and the server was able to control the point much easier (as once in a rally they could still outpower smaller guys).

In this slam maybe the returns are not as defensive and taking control is much harder for the big guys. But a lot more attention to detail would have to take place for us to know if this is true or not.

It could get lower, but I believe the stat is also weighted by player. So if Goffin hits even a couple more aces than average in his next match, the stat would actually go up and it would make the court look faster. But yes, I agree there’s a lot more going on than just this stat. Clearly 2017 was much more dominated by the serve than this year’s edition is, regardless of this relative-ace-frequency stat. It’s more a weird statistical quirk than anything, or else this stat doesn’t actually tell us anything useful at all (which I kind of wonder about, given how widely the men’s and women's numbers tend to vary - if it really captured something about surface speed, wouldn’t it affect both sides similarly?).

 

[mightyrick]

That's a simple way of saying that in the hypothetical case that data and more data appears indicating that they're wrong somehow, you simply stick agreeing with your idols.

No. In layman's terms, it means that if a preponderance of experts disagree with the conclusions drawn from the data, then either the data is wrong or what is being measured is wrong.

If this happened in Operations Research (which it does all the time), we'd go back to work finding the other dependent variables and coefficients (which have a positive correlation) that we missed the first time around.

The presence of data isn't enough. You have to make sure you have the correct data and you have to prove that your data has a positive correlation on the outcome.