Sunday, April 3, 2016

Do stronger players in USTA League play singles or doubles? Interesting Tennis League Stats

In my work generating reports but also in questions I get in e-mail in response to my NTRP Ratings FAQ, a question I often get asked is if a player should play singles or doubles to improve their rating the most.  There is no clear answer, it all depends on the ratings of the players in the match and the score, and some players are simply better singles players than doubles or vice versa, so there is no golden rule.

However, I've told lots of people that singles can offer more opportunity to improve your rating as stronger players typically play singles.  This is the conventional wisdom, that the best players play singles, so beating them will result in a better match rating than beating lower rated players on a doubles court.  There are exceptions to this of course as the rating of your partner matters too, but I wanted to test this conventional wisdom to see if it was indeed true.

So, I looked at 2015 leagues in the 18 & over division, and used my Estimated Dynamic NTRP Ratings as of the end of 2015 to calculate the average rating by court for each gender.

In the charts below, I show the average for each NTRP level showing 1S, 2S, 1D, 2D, then 3D in the groupings.  I've also normalized the ratings to be relative to the bottom of each level so that the relative strength within the levels can easily be compared.

First the men.

From the chart, it is pretty clear that the strongest court on average is court 1 singles, and that the lower courts (2 and 3) have lower rated players on average than higher courts.  What is interesting is that court 2 singles is on average lower than court 1 doubles, but it is stronger than court 2 doubles.

Another interesting datapoint is that at the 5.0 level, there is a little aberration from the norm and court 3 doubles is actually slightly stronger than court 2 singles or doubles.  Note that a lot of 5.0 leagues are just 1 singles court and 2 doubles courts though so that likely skews these numbers some.

But back to singles vs doubles, this chart would seem to largely support the notion that stronger players play singles, except that court 1 doubles is usually stronger than court 2 singles.

Another interesting observation is that as the NTRP level increases, the average rating for every court is less and less above the bottom of the level.  This sort of makes sense, since I used year-end ratings, these reflect how much players have improved during the year, and 2.5s and 3.0s are going to improve a lot more than 4.5s and 5.0s.  Also, at the higher levels the distribution of players is going to be at the lower end of the level.

Last, it appears captains do generally play straight-up and play stronger players on the lower numbered courts.  The USTA does not require this, captains can and do stack their courts to try and steal a win, but it doesn't look like stacking is done nearly enough to skew the data much at all.

Now the women.

The women look largely the same, but sometimes court 2 doubles has a higher average than court 1 singles which was not the case for the men.  The women also seem to fall off a bit more on court 3 doubles than the men.

So there is a slight bias towards singles being stronger than doubles, but not nearly as distinct as for the men.

Also, the women seem to have generally slightly lower averages across the board on each court.  My hypothesis would be (from experience doing reports and looking at where players play) that more women play up than men and so this pulls the averages down.  But I'll do some research to confirm this soon.