Indian Wells briefing: part 1

Starting this week near Palm Springs, California, is a Masters 1000 event at Indian Wells. There are nine Masters 1000 events on the ATP calendar and they are second only to the four grand slams in terms of importance and the ranking points that players earn.

Indian Wells is followed by a second Masters 1000 event in Miami, Florida, and the stature of the two events suitably rounds off the first quarter of the calendar, before the tour moves to European clay. The tournament at Indian Wells is informally considered the tour’s “fifth slam” given its facilities and prize money.

Accordingly, to give Indian Wells its due, this post is the first of three data-driven briefings on the upcoming tournament. Today, I will focus on the tournament in history, specifically: the speed of playing conditions; and the players who have had success at the tournament. Tomorrow’s and Wednesday’s briefings will examine the credentials of the main draw entrants, again from a statistical perspective.

Playing conditions

Indian Wells is situated in Palm desert. Thin dry desert air typically makes the ball travel faster. However, the speed of playing conditions is also determined by a number of other factors, most obviously: the court surface (eg clay, grass), the ball speed, temperature/humidity, altitude (eg Bogota at 2,625m), indoors/outdoors. Overall, the impact of these factors is variable and a little bit of guesswork because no official test exists to measure the speed of playing conditions at different tournaments.

Those trying to assess the speed of playing conditions instead have to parse the statements of players and tournament officials, much of which straddles kidology and/or diplomacy. This in Indian Wells from 2012 (the last time Federer beat Nadal):

Federer: “I think this [Indian Wells] and Miami probably plays best for Rafa on hard court, you know, because it’s very slow.”

Nadal: “The ball flies quick here. The ball is fast, my opinion, and the surface is normal hard court. Not quicker than the rest; not slower than the rest…I like this court. I don’t know, maybe next year will be much faster if Roger says, no?

Tournament organisers have also been involved. Witness this exchange also from 2012:

Question [from journalist]: Regarding the surface and the ball, talking to the players they all say the surface here is on the slow side, balls tend to get very big, and it’s difficult to finish the points. Is it something that is under consideration?

CHARLIE PASARELL [former owner of Indian Wells]: I remember one day standing there and one player came in and says, this court is too slow. You have to speed it up. I said, Really? The other player came in and says, Are you kidding? The court is still too fast, you know. And all you have to do is look at the list of winners that we have had over the years and who’s a big server, fast player, and who is somebody that stays in the back court, plays in the plays in the back court, and it all evens out.

All is not lost, though: we can move from opinion into data.

There is a data-driven methodology that I use to map the speed of playing conditions. It is necessarily a rule-of-thumb metric, given the absence of technological measurement. The methodology is based on multiplying the two game scores in each set to get a metric known as cross courts or XC (for example 7-6; 7 x 6 = 42). The methodology is set out at the bottom of this post. I have measured the average XCs of ATP main draw matches played at Indian Wells since 2002 (1,044 completed matches) and compared those to all ATP main draw outdoor hard court matches also since 2002 (over 12,000 completed matches). The rule of thumb: the higher the XC, the higher the likelihood of quicker playing conditions.

You can see from the chart below that over the course of the last 12 years, and despite being located in the desert, playing conditions at Indian Wells are on average no quicker than those on the ATP tour. In fact, in 8 out of 12 years, conditions are slower than average outdoor hard court conditions.

Average XC for Indian Wells matches vs all hard court matches 2002-2013

20 Indian Wells XC chart

Sands of time

A more qualitative indication of the likely speed of playing conditions is to look at the mix of players that have had success at Indian Wells since 2002. Here are the semi finalists since 2002.

Semi finalists at Indian Wells since 2002

20 Indian Wells SF table

The semi-finalists display a neat balance of typical baseline players (what Pasarell above calls “somebody that plays in the back court”) as well as more obviously attacking players whose games are based around their serve (“a big server, a fast player”). In the table above, Nadal, Hewitt, Kuerten and Agassi are examples of the former category; Henman, Ljubicic, Todd Martin examples in the latter category. In essence, all types of players have flourished at Indian Wells.

Summary

The thin desert air may provide an element of speed to playing conditions but overall, influences such as court surface and ball type make the playing conditions either average speed or slightly slower than average speed. Historically, all types of players have had success at Indian Wells; all types of player will consider themselves to have a chance.

It is very much game on.

Tomorrow: who’s in the mix for 2014?

***

Methodology

It’s easier to hold serve on a faster court than a slower court. Intuition tells you it’s true, so do stats. This from heavytopspin.com: “in 2012, service breaks accounted for 22.0% of games on clay, against 20.5% of games on hard”. Accordingly, on quicker surfaces the score lines of sets are tighter: more tie breaks, 7-5, 6-4 set score lines. We can as a result measure the speed of playing conditions according to a calculation known as cross-courts, a betting market from Sporting Index and others. Under the cross-court markets (hereafter known as XC), the two game scores in each set are multiplied together. So a set that finishes 7-6 scores 42 XCs; 6-4 will score 24 XCs. A match that finishes 6-4 3-6 7-6 will score 84. The higher the XCs, the faster the playing conditions: not always, but typically.

Measuring XC is a more reliable indicator of the speed of playing conditions than the total games of matches. There are 23 games each in matches that finish 7-6 6-4 and 6-1 2-6 6-2. But data tells us which one typically comes from a grass court and which from a clay court. In the former score line XC will score 66; the latter 30.

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