Homogenized surfaces myth or fact?

First topic message reminder :

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

Here again, the most diverse results occurred during the 5-year span from 2003 to 2007, when hard-court aces were 51.3% higher than clay-court aces.  Since then, the difference has fallen to 46%, still a relatively large gap, one that only occurred in two single years before 2003.

If surfaces are converging, why is there a bigger difference in aces now than there was 10, 15, or 20 years ago? Why don’t we see hard-court break rates getting any closer to clay-court break rates?

However fast or high balls are bouncing off of today’s tennis surfaces, courts just aren’t playing any less diversely than they used to.  In the last 20 years, the game has changed in any number of ways, some of which can make hard-court matches look like clay-court contests and vice versa.  But with the profiles of clay and hard courts relatively unchanged over the last 20 years, it’s time for pundits to find something else to complain about.


I encourage you all to look at the graphs and the whole article. Basically the writer states that ace rate differences between clay and hardcourt has not decreased and the difference in breaking on hard courts and clay courts also has not decreased. Meaning that in recent years going back to the 90s the numbers have been pretty stable. If the surfaces have been homogenized you would expect a smaller difference in break rates and ace rates between hardcourts and clay courts. However this is not happening. I didn't find this but saw it on another site so credit to the writer. We have heard a lot on this site and others that homogenization is killing the game but this writer provides strong evidence that debunks the idea of homogenized surfaces.

So what has created the dominant base line game and the end of S and V. Well I have always maintained that it is the better racquets and the better strings and that seems to be the case. Coming in is risky, you can miss the volley or get passed. When you can win the point by blasting winners more easily from either wing then why take the risk of coming into the net. A short forehand will suffice, in the past to finish points you just had to get to the net. It is very difficult for example to hit winners from the baseline with a wooden racquet.

@BS/@SoCal... for your reading pleasure...

2. KEY PROPERTIES
The key properties of a court surface are as follows:
Friction: The resistance to relative movement between a court surface and an object in contact with that surface. The coefficient of friction (COF) is the ratio of the horizontal and the vertical components of force between the ball and the surface. A rougher surface has a greater COF, causing a greater reduction in the horizontal velocity and the surface to play ‘slower’.
Energy restitution: The energy returned by the surface (and ball) following impact. A decrease in energy return is manifested as a reduction in vertical velocity of the ball after impact. The coefficient of restitution (COR) is the ratio of the vertical velocity of the ball after the bounce to that before impact. A surface that yields a higher COR is typically perceived to play slower, because the player has more time to reach the ball.
Topography and dimensions: The geometric regularity of the surface (evenness); the gradient (slope) and planarity designed to assist drainage; and the relative locations of court markings (dimensions).
Consistency: The uniformity of surface properties over the entire playing area and their stability with time, use and maintenance.


http://www.itftennis.com/media/165935/165935.pdf

List of Paris Masters surfaces and winners...

2013 - Hard, Acrylic on Wood - Djokovic
2012 - Hard, Acrylic on Wood - Ferrer
2011 - Hard, Acrylic on Wood - Federer
2010 - Hard, Greenset on Boards - Soderling
2009 - Hard, Gerflor - Djokovic
2008 - Hard - Tsonga
2007 - Hard - Nalbandian
2006 - TaraFlex - Davydenko
2005 - Gerflor - Berdych
2004 - Carpet - Safin
2003 - Gerflor - Henman
2002 - Gerflor - Safin
2001 - TaraFlex - Grosjean
2000 - Carpet - Safin
1999 - Carpet - Agassi
1998 - Carpet - Rusedski
1997 - Carpet - Sampras
1996 - Carpet - Enqvist
1995 - Carpet - Sampras

The number of aces/bps can also be counted for each match, if needed, at a  single tournament  to show aces/bps/surface correlation, which is a much better method than comparing across surfaces.

I get it Laverfan, but the relationship is very direct between aces and courts speed. The same player serving against the same opponent will produce more aces on a faster court the vast majority of times. Yes one match one guy might have a stiff shoulder or the other guy might be playing better or worse this is taken care of by sample size. And if you want to go with what the TD says well according to the TD at the USO the court has not been slowed down at all since 2003 contrary to this idea of ever slowing hardcourts over the last few years that we here from pundits and on the web. I would of course take into consideration what any TD would have to say from the other tournament. And nowhere do I or the author of this piece indicate that this is the only measure of surface speed. It is one indicator that should have direct relationship to break percentage and aces.

laverfan wrote:

Born Slippy wrote:"Coming in is risky, only if the opponent has the ability to chase the ball indefinitely. "

It's precisely the opposite. Coming into the net shortens the points and makes stamina less relevant. It also makes it far harder for a retriever because they have less time to react. Coming in is risky if you are playing exceptional baseliners - which most of the tour are now.

Running towards the net also requires stamina, that too right after the serve. The current base-liners are aided by technologies.

socal1976 wrote:I am sure Kuerten hit more aces on hardcourt than Ferrer

Now, should we compare Isner vs Kuerten? "Pairing" assumes that the each "human" plays at the same level every day like an automaton over the years. Hence my reference to mechanical vs human.

socal1976 wrote: there is a correlation between aces and service speeds.

I assume you meant surface speeds. Serena can hit an ace in Miami 2014 at 119 miles an hour, but Raonic requires 131 mph on the same surface, so surface speed is not the only factor to serve an ace. "Pairing" is trying to eliminate the returner, but does not account for the "human" factor.

Coming to the net requires less energy than staying back and engaging in 20 shot rallies. I agree that technology has aided the returners - thats the point both Socal and I have made. Racquet technology and improved groundstrokes make SV a risky play NOT fitness which was your initial argument.

As for the mechanical point, again its an argument if comparing two individual matches. It has no relevance if the sample size is large enough.

laverfan wrote:

socal1976 wrote:For example, scientists have never seen a black hole but they know that it is there because of its impact. The same analogy is drawn here, he uses two valid and relevant indicators that are directly related to the speed of the court.

The impact of a black hole is due to many factors, like gravity, density, mass. You just keep saying the impact is due to mass alone.

Global warming?

As BS says, the data is fine, but it's correlation to surface speeds is not the only parameter in the equation. For example temperature makes a difference, as does wind, as does humidity.

If Aces = (K) Surface Speed, it assumes a linear (inverse or direct) relationship. It is an approximation, which is why I disagree with the OP.

I had much rather rely on a TD telling me the coefficient of friction and restitution of a surface.

You are creating a straw man to argue with here. The OP doesn't even use aces in the way you suggest. As for the coefficients, that sounds very useful evidence. Do you have it?

As for Rod and Goran, both relied on big serves but Goran (on grass at least) served volleyed on more or less every point. Roddick might have SVed on the odd point but primarily he stayed back. I have watched a few games of their 2001 match just to check my recollection and Goran SVed on every point. Roddick SVed on none in the small sample I watched.

One possibility is that the clay surface has not slowed down, but other factors esp. the balls, have slowed clay down. There is then a corresponding slow down in hard court conditions, including surface changes.
Overall everything slows down.
That's not strictly homogenisation of the conditions, but certainly leads to homogenisation of the game. Once conditions are slow enough, it becomes a baseline game, with more wars of attrition and stamina on both surfaces.
Surely no-one disputes that overall the conditions slowed considerably when comparing 2000 and 2010? And that the physical element of the game has increased greatly?

Possible but unlikely. Usually the argument is that the balls they use on clay are slightly faster now. I don't doubt that a number of hard courts are slower now but my view is that the impact may be somewhat overstated. The article seems to support that position.

Surely no-one disputes that overall the conditions slowed considerably when comparing 2000 and 2010? And that the physical element of the game has increased greatly?

Hi Socal,

The problem I have here is not the conclusion you have reached (although this has been determined beforehand which is not helpful) but the way in which the data has been analysed. It is GCSE level at best and doesn't show any kind of statistical analysis what so ever. To bring in the science used in determining the existence of Black Holes to prove a point did make me chuckle.

Where is the p-value or alpha value? What is the significance level used (sigma) and finally has there been a Chi-Squared Test done on the sample population to determine if we have a large enough sample size. These are the types of statistical tests that are done on any given data (fairly routinely in any subject) to see if the results have occurred by chance or not. Just showing a couple of trend lines (without any working out shown) from an anonymous author on a Blog is hardly conclusive evidence.

The data within the blog doesn't make any reference to strings and racquet technology being the driver behind the game becoming more baseline dominated. Discounting one factor - the homogenising of court speed (which the blog hasn't done in my eyes) - does not validate any other theory which may or may not be a factor.

One other point which no one has covered is what is the preference (or ability) of the individual? What if more kids want to play like Agassi instead of Becker? What if the kid doesn't have the natural ability of Federer or Edberg and is more like Granollers or Ferrer. Do coaches possess the skills to teach volleying? What if their preference is baseline play?

Reading through the blog it seems that most posters accept that the GS surface speeds have become homogenised and with the removal of certain surfaces (wood and carpet) this has exacerbated the issue. Therefore it is obvious that the tour as a whole has become more homogenised with regards playing surfaces. This 'study' focuses on a much narrower band of playing surfaces i.e. clay and hard which doesn't really change that fact.

Jonny. No one is saying this article is conclusive proof of anything. Its clearly not been conducted with rigorous statistical processing standards. I have not checked the figures and they could be completely wrong.

However, it doesn't seem to me that anyone else on this thread has come up with a conclusive way to address court speed issues. The process followed to me seems logical and if as he suggests he has 80-100 examples per year then that seems enough to me to give some reliability to the data, assuming his calcs are right.

Born Slippy wrote:You are creating a straw man to argue with here. The OP doesn't even use aces in the way you suggest.

There is a very clear statistic which SoCal (and OP) refuse to use and instead have come with a convoluted and indirect method of arguing about surface speeds. It is very well tracked and documented for almost 40 years and it accounts for the conditions on the court very well and folds technology into itself.

I propose we use the duration of a single Tennis game across surfaces between Nadal and Djokovic as a measure of surface homogenization using their 30+ matches well documented by ITF/ATP. Murray v Djokovic or Murray v Nadal can be secondary evidence. Wilander matches should be used from the noughties.

Also, from the OP...

In the last 20 years, the game has changed in any number of ways, some of which can make hard-court matches look like clay-court contests and vice versa.

This is very telling.

Born Slippy wrote:As for the coefficients, that sounds very useful evidence. Do you have it?

No, ITF publishes coefficients by deriving the 5 Categories from the mu and COP. See the PDF link (page 37). See also Table 2 and 3 on page 38 and 39.

As part of the assessment procedure, each surface product is awarded a Court Pace Rating, which classifies it as a slow (Category 1), medium-slow (Category 2), medium (Category 3), medium-fast (Category 4) or fast (Category 5) surface. This change follows a two- year research project by the ITF Technical Centre, which led to the development of Court Pace Rating, which provides better agreement between theoretical measurements and player perception of pace than for its predecessor (Surface Pace Rating).

Born Slippy wrote:Jonny. No one is saying this article is conclusive proof of anything. Its clearly not been conducted with rigorous statistical processing standards. I have not checked the figures and they could be completely wrong.

However, it doesn't seem to me that anyone else on this thread has come up with a conclusive way to address court speed issues. The process followed to me seems logical and if as he suggests he has 80-100 examples per year then that seems enough to me to give some reliability to the data, assuming his calcs are right.

Yes BS I was wary about posting all that tbh. I realise it's a bit over the top given what we are discussing here. But I just wanted to make the point that it's not as you say conclusive proof of anything and is more than open to challenge.

As I said earlier I think it's a combination of a lot of factors that has led to the demise of S&V and more baseline orientated tennis. Attributing one factor above another would take the kind of statistical analysis mentioned. Even then it's open to challenge. Academics, politicians, pundits, children, football fans..name any cohort you like, they've all got one thing in common.....they like to disagree! The only difference is the language they use!

Born Slippy wrote:No one is saying this article is conclusive proof of anything. Its clearly not been conducted with rigorous statistical processing standards. I have not checked the figures and they could be completely wrong.

There are no published figures except two graphs. There is no raw data, no player names in paired match ups, or tourney dates or surfaces. This is an arbitrary conclusion.

Born Slippy wrote:However, it doesn't seem to me that anyone else on this thread has come up with a conclusive way to address court speed issues. The process followed to me seems logical and if as he suggests he has 80-100 examples per year then that seems enough to me to give some reliability to the data, assuming his calcs are right.

You refuse to look at the ITF categories. I also posted Paris surface/winners over last 15 years (1995+). Carpet from ITF was Category 5, TaraFlex in 2006 is the last Category 5 used. Gerflor in 2009 became Category 4.

Like the Blog quoted in the OP here is another (and IMHO a better approach) - http://www.perfect-tennis.co.uk/tennis-court-surfaces-and-court-speeds/

(Caveat: The blog is apparently written by a Federer fan and may not be palatable to some).

It is a pity that ITF/ATP refuses to publish the Category every year. The Daily variations do affect this as well.

When you use statistical data in support of a theory, it would be useful to provide the source where this data comes from. I gave a look (very quickly I admit) to the blog and what I could see was only a couple of low quality Excel graphs and no source at all. Nor I could find much information about the author of the blog. It might even be a Socal's blog for what I could see..........

Very interesting article Laver but, if Im reading it right, he appears to conclude that we can't place any reliance on the ITF's court speeds as they probably don't reflect the actual courts at the tournaments? That said, it would be interesting to compare the courts used in 2003/2007 at each event he mentions and see how many had changed grade. His conclusion is we just have to use our own eyes. I can't see it but do I assume he posts a link to the Federer serve speeds - the one where the 2003 serve appears to hit the line?

I don't get the first part of your 12.02 post at all. Are you saying match length is a better way of judging court speed than aces?

Instead of the blog referenced in the OP, I prefer to read this...

http://www.bbc.co.uk/dna/606/A47408808

Born Slippy wrote:Very interesting article Laver but, if Im reading it right, he appears to conclude that we can't place any reliance on the ITF's court speeds as they probably don't reflect the actual courts at the tournaments? That said, it would be interesting to compare the courts used in 2003/2007 at each event he mentions and see how many had changed grade. His conclusion is we just have to use our own eyes. I can't see it but do I assume he posts a link to the Federer serve speeds - the one where the 2003 serve appears to hit the line?

I will try and find some reliable data.

Born Slippy wrote:I don't get the first part of your 12.02 post at all. Are you saying match length is a better way of judging court speed than aces?

In the previous post (with the BBC 606 link), a different metric (Games Per Second) is used. If the GPS number gets closer between surfaces, for any reason whatsoever, the conclusion, IMVHO is homogenization. Wilander agrees, Gilbert agrees, Many Pros who actually play on courts agree. We are not discussing the motivations for such actions, which can be a separate topic by itself.

I can accept GPS as a theoretical way of considering court speed albeit I would have my doubts as to whether it is a better reflection than aces. So has the GPS become closer?

Born Slippy wrote:I can accept GPS as a theoretical way of considering court speed albeit I would have my doubts as to whether it is a better reflection than aces. So has the GPS become closer?

Let me do some analysis, and I will post the data and results in a new thread. It may take me a couple of days.