Saturday, February 18, 2017

If you go to USTA League Nationals, will you be bumped up? Interesting Tennis League Stats

A fairly commonly held belief is that if a player goes to Nationals, they will, or should, be bumped up.  We know this doesn't happen though, and it causes much consternation among a few that think it is unfair that someone goes to Nationals and doesn't get bumped up and so has a chance to go back again at the same level.  There are of course other rules that preclude the same team going back at the same level, e.g. the move-up/split-up rule where only three members from a team that goes to Nationals can be on the same team at the same level the following year.

But back on topic, I did some research to see how many Nationals players actually do get bumped up so we could see some real statistics on the subject.

First, I took a look at all the players on the roster of an 18+ Nationals team that held a 2015 year-end C rating and ended 2016 with a C rating.

This revealed that 67.3% stayed the same level, 31.2% were bumped up, and perhaps surprisingly, 1.5% were bumped down!

Now, some teams have large rosters and not everyone is at the top of their level and "Nationals caliber", and not all players will actually go and play in a match.  Here is how it looks if just those that played in a match are included.

Here the bump up rate goes up to 37.2% while the stay rate is 61.9% and just 0.1% of these are bumped down.  This probably makes sense, the players on a roster that don't play are likely lower rated so removing them the rate goes up, but the bump up percentage is still below 40% which goes against the perception that if you go to Nationals you will be bumped up.

Second, I did the same for 40+.  Here is the rostered player chart.

For those on Nationals rosters, 67.8% stayed the same, 29.5% were bumped up, and 2.7% were bumped down.

Then the players that played at Nationals.

Of those that played, 63.9% stayed the same, 33.9% were bumped up, and 2.1% were bumped down.

These 40+ numbers probably make sense, the bump up rate is lower in the first place as those 40+ are less likely to be improving as much and the bump down rate is higher as there are older players more likely to be on the decline.  And we see a similar small increase in the bump ups looking at the players that actually play.

Note, that this analysis did not include self-rates, and the self-rates that make it to Nationals could very well have higher bump up rates.  I'll try to do this analysis soon.

Also, even just the 18+ and 40+ analysis above can be sliced a variety of different way including by gender, by level, and also looking at the teams that made the semis.  If there is interest, leave a comment here or on Facebook and let me know what you'd like to see!