Saturday, June 21, 2008

Wimbledon 2008 Preview, Aging Patterns of Female Tennis Players

My interest in tennis is probably about as high as it's ever been. I had more fun watching the French Open than any other sporting event this year (particularly the semifinal match between Ana Ivanovic and Jelena Jankovic), and I think the game has more interesting figures than it has since the late 70s-early 80s, back when McEnroe-Borg-Connors and Evert-Navritolova were the stars.

The main reason I am making this post, though, is to comment on aging patterns in elite female tennis players.

Women's Preview:
My sense is that there are a distinct grouping of players who are well-suited to grass right now- players with powerful serves and groundstrokes. Venus Williams is the archetype of this player, and when she is at her best, I think she's probably the best grass player of all-time (with respectful nods to Martina Navritolova and Steffi Graf). The players in the current draw that I would put into this grouping, and thus the co-favorites, would include Venus and Serena Williams, Maria Sharapova, Ana Ivanovic, and Dinara Safina. There are a few others who also have this type of game, like Svetlana Kuzsetnova, Lindsay Davenport, and Amelie Mauresmo, but I would put them all step-down from the other 5 right now.

Of the non- "big babe" style players, I think that Jelena Jankovic is clearly the best player and biggest threat to win. I think, however, it would be hard for her to compensate sufficiently for her lack of a dominating serve or forehand, no matter how fit, fast, and flexible she is.

So, how would I rank the big 5?
1. Ana Ivanovic
2. Maria Sharapova
3. Serena Williams
4. Dinara Safina
5. Venus Williams

I would probably throw Jelena Jankovic in there somewhere, but I am not sure exactly where. At their best, I think Safina or Venus would kill Jankovic on grass, but Jankovic is in my mind far more likely to make it to the semifinals based on her consistency (i.e., I don't see JJ losing to a second-tier player, where Venus and Safina definitely might).

I think the distinction for overall favorite comes down to Ivanovic and Sharapova. They are having the best years so far, have split the 2 majors, are about the same age (Sharapova is 7 months older), and have similar games that are well-suited to Wimbledon. Sharapova has a better overall track record and has been elite for 2 more years, while Ivanovic is playing a bit better recently.

The main question in distinguishing the two of them is in determining whether Ivanovic's recent high level of play is transient, or whether she's truly raised her game. I tend to think that latter, which is why I have her above Sharapova. However, I may be completely off-base, and she may be a merely very good player having an unusually good year, like Amelie Mauresmo did in 2006.

I have several reasons for thinking that Ivanovic has raised her game, and that we are seeing the beginning of her ascent as an all-time great:
1. Age. While Sharapova and Ivanovic are almost the same age, they have matured differently. Sharapova looks about the same now as she did when she won Wimbledon in 2004 at age 17. Ivanovic, on the other hand, has done a lot of aging, in a good way. She is more muscular, has considerably less fat, is more mobile, and has greater endurance. 4 years ago, Sharapova was clearly a better overall athlete. That is no longer true. Ivanovic was probably always stronger, but she has now matured to the point, where she is also faster and has more endurance.

The main reason I wanted to include a Wimbledon preview in this blog is to speculate on whether there are variable maturation rates amongst female tennis players. It has been commonly noted that females often become elite tennis players at a younger age than their male counterparts, I don't know that this is universally true. I suspect that players with larger frames, like Ana Ivanovic and Lindsay Davenport, will mature later than their thinner framed counterparts. I also suspect they will have longer lifespans, and that thinner framed players will be more likely to retire at a young age.

One way of assessing this is to look at all of the women who have been ranked #1 by the WTA- that is a reasonable standard for an elite player. There are 17 players who have been ranked #1, starting with Chis Evert in 1975, and as of right now (June 2008) Ana Ivanovic is #17.

For each of the champions, I looked at the correlation of height or weight with 4 different performance measures- # of Grand Slams won, Age when they won their first grand slam, Age when they first reached #1, and Age at Retirement

Depending on the study listed below, I may or may not include all 17 players (it will be clear which players are included). Eve Goolagong is a bit of an odd case, since she is really a player from an earlier era, who for a short time passed Evert for #1. About half the list is currently playing, which limits their inclusion in some parts of the study, retirement dates are in some cases imprecise, and I suspect that many of the weights I have are inaccurate (e.g., I suspect Serena Williams weighs more than Kim Clijsters, and I think Tracy Austin was much lighter than her listed weight).

So here are the results:

Height- not statistically significantly correlated with anything, although taller players did tend to retire at an older age. The former and current #1 players who have not yet retired (Davenport, the Williams sisters, Mauresmo, Sharapova, and Ivanovic) are taller as a group than the players who have currently retired, so they are almost a different group than the players who have retired.

For those who care about the particulars:
#Slams: N=13, r=0.0959, p=0.7552
Age at first slam win: N=17, r=0.0504, p=0.7552
Age when first #1: N=17, r=-0.08918, p=0.7336
Age when retired: N=11, r=0.40262, p=0.2196

For weight, the trends are stronger. The one statistically significant relationship was that heavier players took longer to win their first Grand Slam event. They also won took longer to reach #1, but that wasn't quite statistically significant.

The actual data:
#Slams: N=13, r=-0.16443, p=0.5914
Age when winning first slam: N=17, r=0.527, p=0.0296
Age when first reaching #1: N=16 (excluded Eve Googalong, since dating #1 is unclear with her), r=0.403, p=0.1213
Age at retirement: N=11, r=0.125582, p=0.7129

If anyone is interested in examining the data, I would be happy to send them the excel spreadsheet.

So, this is an awfully long aside- let me get back to comparing Sharapova and Ivanovic. The underlying argument I was trying to make is that the two of them are similar in age, and Sharapova was clearly better for 2004-2006. Over the past 2 years, they've been relatively even, and Ivanovic has probably passed her from Indian Wells on this year. To argue that Ivanovic is actually the better player, I would need to make the case that she is a later maturing player, and that the recent uptick in her performance is a function of late maturation. I argued that players of her build (larger frame) tend to mature at a later age.

While the data above is not as overwhelming as I thought it would be, it does appear to be true that players with larger body frames tend to mature at a later age. I think that is what is happening with Ivanovic.

A few other factors in Ivanovic's favor:
- She just won the French Open, which was on a surface not particularly conducive to her game. Her first serve and especially her forehand were near unreturnable on clay. They will be even more dominant on grass.
- Her coaches and trainers stated that they were operating on a long term plan, with the goal of peaking in a few years. That is consistent with her play. Even between the Australian Open and French Open of this year, you could see big differences in her game, especially her footwork. That she could reach #1 while her game is still evolving is encouraging.
- She's had #1 talent for several years, and the main question with her has been her temperament. I think many were concerned she was another Amelie Mauresmo or Kim Clijsters, and too nice to consistently win at the highest level. Winning her first tournament, and doing so in dominant fashion, should help her going forward.
- I think she's very comparable to Lindsay Davenport, but perhaps a bit more athletic and mobile. Lindsay was also able to reach #1 before her game really matured, and continued to improve as a player, primarily because of improvements in her fitness.

I might be completely off-base, but I think Ivanovic is just now starting to emerge as the next superstar. I don't know that she'll reach the Evert-Navritolova-Graf level of superstardom, but I don't think it's unreasonable that she'll be a player of the stature of at least Davenport, if not Seles or even better. It will be fun to watch.

Back to the Ivanovic-Sharapova comparison. They are awfully close. I think Ivanovic has a better first serve, but that Sharapova is more consistent with her second serve. Ivanovic's forehand is better, but Sharapova has a better backhand. I think Ivanovic's biggest edge now is her mobility- I think clay made that more apparent. Sharapova's real edge was in her competitiveness and intensity, but I don't know if that is really there anymore- Ivanovic has made 3 of the last 5 finals. It's close, but I give the edge to Ivanovic.

The third person who might fit into this discussion is Dinara Safina. She is also a late bloomer. Part of this might be part of the same phenomenon- she's also an awfully big girl. I am guessing that Safina is the strongest woman on the tour, although Serena Williams and Lindsay Davenport are probably pretty close. But Safina has another reason that she might be a late bloomer- namely, that's she's a bit (how to put this delicately) .... emotional. At the French, she was able to harness that emotion for the most part. If that is real, then I think she's a contender for the near future. If not, then she'll be like her brother- always a threat to win or combust.

So, those are my thoughts for now. Can't wait for the tournament to start.

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