Still a relevant point on the subject of surface speeds

[Russeljones]

This struck me as a very good post on a subject, the complexity of which is systematically underrated here.

by wholesight

I think one problem here is something that economist Dylan Evans has pointed to in his writings about risk assessment: namely, that verbal labels for complex phenomena are inherently susceptible to varying interpretation – so much so that they make agreement nearly impossible. And the problem is not necessarily solved by creating a mathematical measure (that is, a probability) for a given label – because people will *still* insist on interpreting the label differently (often without being aware of what they are doing), and thus will interpret what the probability “means” in very different ways.

To get pedantic for a moment, the example Evans uses is that the Intergovernmental Panel on Climate Change has stated in reports on global warming that it uses the label “unlikely” to refer to events with have an estimated probability of less than 33 percent, and “very likely” to refer to events with an estimated probability of at least 90 percent. But research elsewhere (e.g. a study in 2009 in the journal “Psychological Science” showed that some persons privately interpret the label “unlikely” as including events with as much as a 66 percent probability – twice the threshold intended by the Panel on Climate Change.

So back to tennis – it appears we have some readers who dispute the use of math to explore court speed by saying they disagree with the very notion that math can even be used for this purpose – they assert that the phenomenon is simply too complex. I suspect the real problem here is that such readers are as bad at math as I am, but don’t want to admit it! And on the other hand, more usefully, we have readers who more reasonably suggest that ace count isn’t enough & that other data should be collected.

This gives me an idea. Obviously some data simply aren’t available that might be useful. But . . . if someone who was good at math had infinite time and personal access to players at least at the challenger level or better . . . it seems to me there would be a way to generate useful additional data anyway, as follows: First, select a group of challenger-or-better players who would be willing to be interviewed periodically about their experience after playing a particular court. This could be done several times during the year so as to collect data on X many different court compositions. The interviews would need to be done *immediately* after the player concluded a match on a given surface, so that their recollections would be fresh. The interview technique would be similar to that espoused by expert knowledge researcher Gary Klein (“Sources of Power,” etc.). The goal of the interview would be to first illicit whether the player considered the surface in question to be fast, slow, medium, or what have you – after which the interviewer would ask open-ended questions about what the player’s actual *experience* was that suggested this fastness or slowness. After this, the researcher could see what data might be linked to the verbal labels that had been expounded on in such detail.

For example, we might find that a low bounce height is closely married to a player’s subjective impression of fastness. We might speculate that a low bounce takes away reaction time during rallies and when returning as well. But the key would be to see if the data for this metric matched up with the extended verbal descriptions from the players. Etc. etc.

I meant to add that even data like “bounce height” are not really singular, but packages – i.e. not just the court but the type of ball & the weather will affect “bounce height.” That introduces some slop into the data that are actually available.

But more pertinently, it seems to me that a limitation with numerical analysis will always be that complex phenomena – i.e. any event in the natural world – can never, in the end, truly be unpacked into discrete events. A comparison is how we speak about water: if we measure by atom count, we might be tempted to say that hydrogen is more responsible for making up water than is oxygen. But if we measured by molecular weights, we might be tempted to say that really, oxygen is more important to a water molecule, since it outweighs the hydrogen. But the fact is, for many discussions, such attempts at dissection into separate components are not useful for understanding “water” as we experience it.

So too, the questions about court speed are much more entangled than our wording sometimes suggests. “Speed” is not something a court possesses in isolation. It might be more appropriate to talk of “how fast a court ‘plays’,” with the emphasis on the verb (“plays”) since verbs are much more suggestive of the interplay involved.

Any thoughts?

 

[coloskier]

A few things come to mind...

1. If the ball bounces higher, you have more time to get ready for the ball, thus the "slow court" moniker. You can wait for the ball to come back down and play 10 feet behind the baseline, a la Nadal.
2. If the court bounces lower, it is usually due to the ball "skipping" through the court, which decreases the time you have to prepare for the shot, thus the "fast court" moniker. Also, you have less time to pick up the ball as it drops, and playing 10 feet behind the baseline can be a disaster.
3. If a player plays on the baseline, he makes the court faster for no other reason than the opponent has less time to react, a la Fed and Agassi. Thus giving a court a "fast court" moniker.
4. If a player plays 10 feet behind the baseline, the opponent has much more time to react, giving the court a "slow court" moniker.

So, you have two different scenarios which can change a "court speed". The actual court itself, and the style of play the player uses.

 

[Russeljones]

A few things come to mind...

1. If the ball bounces higher, you have more time to get ready for the ball, thus the "slow court" moniker. You can wait for the ball to come back down and play 10 feet behind the baseline, a la Nadal.
2. If the court bounces lower, it is usually due to the ball "skipping" through the court, which decreases the time you have to prepare for the shot, thus the "fast court" moniker. Also, you have less time to pick up the ball as it drops, and playing 10 feet behind the baseline can be a disaster.
3. If a player plays on the baseline, he makes the court faster for no other reason than the opponent has less time to react, a la Fed and Agassi. Thus giving a court a "fast court" moniker.
4. If a player plays 10 feet behind the baseline, the opponent has much more time to react, giving the court a "slow court" moniker.

So, you have two different scenarios which can change a "court speed". The actual court itself, and the style of play the player uses.

Don't forget the balls themselves.

 

[Inanimate_object]

Interesting post, not sure I agree with it.

1. Most importantly, no one here has done "math", they have simply used numbers. There is a HUGE difference between the two.

2. wholesight suggests the metrics devised are sound, but people get confused when attaching lexical tags to those metrics. I don't think that's true at all. No one disputes that 17 is "greater" than 14. What they dispute is the validity of the metric itself. Most quantitative studies are devised around a numerical parameter, and lexical tags come after, whereas here, it seems people want to validate a lexical term such as "Greatest of All Time" with no definitive answer on which metric to use.

3. His point about statistics and complex phenomena is just nonsense. Statistics has never been about "de-randomizing" random events. It's about understanding the randomness structure of random events, and ALL random events in the universe have a randomness structure.

4. The idea of polling players immediately after completing matches just leaves the accuracy of the metric at the mercy of players' prejudices as opposed to the audience's prejudices. Just as verbs mean different things for the audience, so to do they have different interpretations by players.

I think this is a good post, if only to show that people in general don't know what they're talking about when they throw around numbers. Numbers don't validate anything on their own.

 

[Russeljones]

Interesting post, not sure I agree with it.

1. Most importantly, no one here has done "math", they have simply used numbers. There is a HUGE difference between the two.

2. wholesight suggests the metrics devised are sound, but people get confused when attaching lexical tags to those metrics. I don't think that's true at all. No one disputes that 17 is "greater" than 14. What they dispute is the validity of the metric itself. Most quantitative studies are devised around a numerical parameter, and lexical tags come after, whereas here, it seems people want to validate a lexical term such as "Greatest of All Time" with no definitive answer on which metric to use.

3. His point about statistics and complex phenomena is just nonsense. Statistics has never been about "de-randomizing" random events. It's about understanding the randomness structure of random events, and ALL random events in the universe have a randomness structure.

4. The idea of polling players immediately after completing matches just leaves the accuracy of the metric at the mercy of players' prejudices as opposed to the audience's prejudices. Just as verbs mean different things for the audience, so to do they have different interpretations by players.

I think this is a good post, if only to show that people in general don't know what they're talking about when they throw around numbers. Numbers don't validate anything on their own.

He is responding to a blog post where there is an attemped mathematical approach to explain the fact behind the surface homogenization narrative. I will link the article tomorrow.

 

[Russeljones]

Here's the article he is responding to. Note the virtual omittance of the subject of improved racket/string technology from an article attempting to debunk the surfaces slowing phenomenon through serve/return stats.

http://heavytopspin.com/2013/04/08/the-mirage-of-surface-speed-convergence/

 

[Inanimate_object]

the point still stands. It is using numbers, not math.

 

[Russeljones]

the point still stands. It is using numbers, not math.

That is utter nonsense.

 

[Inanimate_object]

That is utter nonsense.

Goes to show your quantitative illiteracy. Using numbers is not enough to enjoy scientific reasoning. That's like saying typing is screenwriting. There is NOTHING in the article that remotely tries to estimate an unknown parameter with a randomness process. This is a NUMERICAL analysis, not a MATHEMATICAL one. Meaning it is marginally better than a subjective analysis.

 

[Russeljones]

Goes to show your quantitative illiteracy. Using numbers is not enough to enjoy scientific reasoning. That's like saying typing is screenwriting. There is NOTHING in the article that remotely tries to estimate an unknown parameter with a randomness process. This is a NUMERICAL analysis, not a MATHEMATICAL one. Meaning it is marginally better than a subjective analysis.

Superfluous rantings of a pseudo-intellectual on the internet. Seen it all before.

 

[Inanimate_object]

Superfluous rantings of a pseudo-intellectual on the internet. Seen it all before.

If you can grasp that your writing is not on the same level as say Orwell, then you should also be able to understand that using numbers is not the same thing as using the mathematical/statistical process.

 

[Russeljones]

If you can grasp that your writing is not on the same level as say Orwell, then you should also be able to understand that using numbers is not the same thing as using the mathematical/statistical process.

I suppose there is a reason behind the obdurate denial of a plain fact, the numbers are arrived at through mathematics (i.e. nobody provides a stat sheet with ready numbers), but I simply don't care anymore. You bore me.

 

[Inanimate_object]

You still care enough to reply, but not enough to educate yourself on the difference between math and numbers. Your loss. Byebye.

 

[JMR]

Any thoughts?

The proposed project would be a waste of time. The subject is not sufficiently important to warrant such an investment of resources.

 

[Gary Duane]

Russel,

What I would like to see is something like this:

Project a ball from A feet behind the baseline, at height B, starting at velocity C, with spin D (rpm), using ball E, at temperature F, humidity G, altitude H.

If you don't start with exactly the same measurements, you can't measure what is different after the ball hits the court (how far the ball goes until it bounces again, and how high it bounces).

Since it is highly unlikely this will ever be done (as it would require a machine that pops out balls with a controllable angle, speed and amount of spin), I think it becomes obvious that we are simply dealing with too many variables.

This leaves us in the position of using our senses and our intuition to assess what is going on, and in my experience that is simply unreliable.

 

[spinovic]

The proposed project would be a waste of time. The subject is not sufficiently important to warrant such an investment of resources.

I agree. Court conditions are a minor cause for the change in tennis. Racquets and strings are the real driving force. They have forever altered the geometric possibilities on a tennis court. When I first saw Federer, I was amazed by the angles he could create on a tennis court. I'd never seen anything like it. Now almost everyone does it. Thanks to polyester strings. Also, to exaggerate a bit, it has converted tennis from 2D to 3D. Topspin not only allows you to create sharper angles to attack on the xy plane, but the strings and racquets allow such topspin that it can be used as a weapon by itself, in the z plane, if you will. And, not only that, it's a safer shot. Nadal's heavy topspin forehand is not just a safe, rally ball for him, but a real weapon. The bounce backs guys up, or if they choose to stand on the baseline, the spin makes it more difficult to deal with.

Topspin isn't a new discovery, but new technology has turned it into a weapon. Guys can swing out without fear of the ball flying on them. Just compare a typical baseline rally between Borg and McEnroe to one between Federer and Nadal. Players finessed the ball once upon a time with nice, smooth, controlled, fluid motions - compared to what it once was, they bludgeon the ball now.

 

[Russeljones]

Russel,

What I would like to see is something like this:

Project a ball from A feet behind the baseline, at height B, starting at velocity C, with spin D (rpm), using ball E, at temperature F, humidity G, altitude H.

If you don't start with exactly the same measurements, you can't measure what is different after the ball hits the court (how far the ball goes until it bounces again, and how high it bounces).

Since it is highly unlikely this will ever be done (as it would require a machine that pops out balls with a controllable angle, speed and amount of spin), I think it becomes obvious that we are simply dealing with too many variables.

This leaves us in the position of using our senses and our intuition to assess what is going on, and in my experience that is simply unreliable.

There is a great read about this out there, somewhere. I wish I had bookmarked it. The ATP literally invited a rocket scientist to explain to them what happened to the ball once it touched the court surface. I pity those dismissive of the significance of court changes. They fail to appreciate the multiplier effect these changes have.

 

[Nathaniel_Near]

It's all about balance.

If we kept the surfaces and balls the same then the consistent improvements in racket technology and (contentiously and arguably) the overall improvement of the tennis athlete would cause there to be a constant increase in the rate of aces (for example) and therefore a sport that doesn't match up with the aesthetic wishes of the public. So, the balls had to be made heavier and the courts slower to work against improvements in other areas of tennis. Balance, in all things. The implications that taking a reductionist view is dangerous in light of the hugely holistic nature of tennis "playing conditions" is a pertinent one. In readdressing the balance, the pace of the game might be as fast as it used to be but not uniformly, and thus in a different way and in a different overall set of configurations—in order to achieve a similar result.

The band of surface types, playing conditions and thus potentially successful playing styles has been narrowed, so you could say there is too much effort to balance or rather normalise tennis...or rather, not enough variety.

 

[Gary Duane]

It's all about balance.

If we kept the surfaces and balls the same then the consistent improvements in racket technology and (contentiously and arguably) the overall improvement of the tennis athlete would cause there to be a constant increase in the rate of aces (for example) and therefore a sport that doesn't match up with the aesthetic wishes of the public. So, the balls had to be made heavier and the courts slower to work against improvements in other areas of tennis. Balance, in all things. The implications that taking a reductionist view is dangerous in light of the hugely holistic nature of tennis "playing conditions" is a pertinent one. In readdressing the balance, the pace of the game might be as fast as it used to be but not uniformly, and thus in a different way and in a different overall set of configurations—in order to achieve a similar result.

The band of surface types, playing conditions and thus potentially successful playing styles has been narrowed, so you could say there is too much effort to balance or rather normalise tennis...or rather, not enough variety.

Nevertheless, we study SOME of the factors and at least get that part straight. There have been means of delivering balls to players learning to hit for decades. With such machines you have a means of delivering a ball with the same speed and angle, from the same place in the court.

It's not terribly difficult to pick days when the temperature is 80 or 85F, where the humidity is at some level, then pop the balls out and see how they bounce.

That part is not rocket science. You can then use the same ball and see how different courts react. How far does the ball bounce? How high?

I don't know anything about how spin can be varied from a machine. But I suspect balls can be "shot" with X amount of spin, top or bottom. This may not reach the rpms that Nadal uses, but you could see how spin changes the bounce and speed the ball takes off.

From there it is a matter of using the same test for different balls, to see how that changes things.

Strings are not a factor here because HOW the strings produce the speed and spin have nothing to do with how the balls travel after they have been shot out, or struck.

What frustrates me is that people tend to mix facts with guesses based only on their gut and the result is simply useless.

To some extent we can make big statements, and those are mostly like correct.

If the ball bounces high, and it travels a long way after it bounces, you are going to get something like what we see on red clay. We know that because we see players hang way back behind the baseline and wait for the balls to reach the height of their bounce and then start to drop. That's the default return style of Nadal. It works on clay. It absolutely does not work for most people in grass.

We know that a lower bounce can be attacked "on the rise" from the baseline, and we can see Fed do that on grass - and on HCs where the bounce is fairly low.

We know that hitting on the rise starts to fall apart when the bounce is so high that even hitting a ball on the rise may be too high. That explains whey a 1HBH is so dangerous against Nadal's looping spin, and why Fed has only had success against Nadal when the balls bounce low.

But those are big generalities.

What is not clear to me at all is how different kinds of HCs change how the balls reacts when they hit the courts. I keep reading that the courts at the AO are slower. I can't see that. I do see that balls bounce higher, and that translates to "slower" for me because I see that players have more time to return. I see that on "fast" courts the ball bounces lower, and that takes away time.

I don't see any proof whatsoever that the old style grass courts were "faster". What I saw was balls that bounced low, at the best of times, and that often bounced lower and very inconsistently. Players had to avoid rallies at all cost because they could not take the chance that the next ball would even be playable, so there was a race to take the net, which was predictable play.

Now, it may be with the newer strings and bigger rackets that more balls that are not hit cleanly still go back over the net, and the increased top spin means that a lot more badly hit balls will fall short but will still make it over the net. That would have an impact even on grass, and of course the newer grass seems to give a hgher bounce and less bad bounces.

I suspect that HCs and/or clay have changed less than grass courts. I'm not sure of that.

But I still think that the main factor we all talk about when we talk about speed is the time between when the ball strikes the court and when it must be hit, and the biggest factor at any time (assuming same era, same rackets, same technology) has to be the height of the bounce, because that will most of all change the time a player has to stroke the ball.

 

[Gary Duane]

There is a great read about this out there, somewhere. I wish I had bookmarked it. The ATP literally invited a rocket scientist to explain to them what happened to the ball once it touched the court surface. I pity those dismissive of the significance of court changes. They fail to appreciate the multiplier effect these changes have.

I'd love to read that.

Rocket scientists sometimes are incapable of talking to anyone other than fellow rocket scientists, but some are able to break down the big points so that we can understand them.

What bothers me is that non-scientists make up "facts" that have no basis in reality, and then these "facts" become accepted as either the truth or at least things of some importance.

So now we mostly accept that the courts at the AO are slow, which I still believe is more about the height of the bounce than "speed".

That may be the EFFECT of how the balls used there react to the court, and how these things impact the playing style of the pros, but we still have no hard facts whatsoever about whether or not the majority of most shots at the AO bounce higher than they do at the USO.

 

[Nathaniel_Near]

Yes, I have no opposition to testing some parameters, but I'm more referring to trying to judge the changes that have occurred from say the '90s to now. It would be hard to emulate older conditions with great accuracy. They could certainly start implementing tests and studies and monitor the results consistently starting now. It sounds like quite the venture, though.

"What is not clear to me at all is how different kinds of HCs change how the balls reacts when they hit the courts. I keep reading that the courts at the AO are slower. I can't see that. I do see that balls bounce higher, and that translates to "slower" for me because I see that players have more time to return. I see that on "fast" courts the ball bounces lower, and that takes away time.

I don't see any proof whatsoever that the old style grass courts were "faster". What I saw was balls that bounced low, at the best of times, and that often bounced lower and very inconsistently. Players had to avoid rallies at all cost because they could not take the chance that the next ball would even be playable, so there was a race to take the net, which was predictable play."

A few thoughts on this then..

I'm not sure the ball bounces higher on the current Plexicushion surface than it did on Rebound Ace. What seems clear is that Rebound Ace was a more changeable surface where the weather impacted the court conditions more. As for old grass courts, a lot of them do seem to produce an extremely low bounce which tends to take away time and options from the players. Is that the court, the balls, or the more commonplace flatness of strokes? Well knifed slices these days stay extremely low at Wimbledon, still.


"Strings are not a factor here because HOW the strings produce the speed and spin have nothing to do with how the balls travel after they have been shot out, or struck."

Strings are a huge factor in then coming to an overall conclusion about the conditions. We can test specific spins and velocities and such with a machine in controlled conditions so that we know exactly what effects occur, but we can't magically determine what rpm and such that players from older times were generally imparting onto the ball. In other words, we can know what happens now with x spin but can't really use it to come to much more certain conclusions about times that are too far into the past, or even fairly recent... If we could use time travel to send the current gen back into an older time, then we could arrive at far more trustworthy conclusions. But yes, such an initiative could be started now and perhaps there are court types that can be retroactively measured.

 

[Russeljones]

Can you two please take your computing power to The Game That Changed Tennis thread. I want to figure out why more aces were served at Wimbledon 2011 than at 1994. Thank you.

 

[spinovic]

Can you two please take your computing power to The Game That Changed Tennis thread. I want to figure out why more aces were served at Wimbledon 2011 than at 1994. Thank you.

Me too...the stats seem to support 2011 being faster.

 

[Nathaniel_Near]

I'll take a proper look later and respond.

 

[Russeljones]

Is this maths or numbers?