Tuesday, March 31, 2015

Is this USTA League player tanking to manage their dynamic NTRP rating? Or just bad at singles?

I came across a player that on the surface one could accuse of tanking matches to manage their rating, but upon deeper inspection, I'm not sure it is so clear.

The player went 5-3 in the Spring league playing 4.0 but went 0-6 in Fall leagues, one a 3.5 match late in the 2013 calendar year and five more in 2014.  So they are using the Fall league to manage their rating down right?

I'm not so sure.  Here is their chart for last year.

There is clearly a very wide range in the results, and the Fall league matches do stand out as the worse results, but because my Estimated Dynamic NTRP Rating reports break out singles and doubles results both in the summary stats and the chart, it is clear that all the Fall league matches that are the bad results are singles while the Spring league results are all doubles.  There are also some lower rated doubles matches during the Spring so the Fall league results don't stand out too much.

But looking at singles vs doubles, this player's average match ratings are 3.24 vs 3.57, a full 0.33 different.  That is an awfully big spread, in most of the reports I do for players their difference is just a tenth or two, but not over three tenths.

So is this player tanking matches?  Or are they just bad a singles?  The data would seem to lean towards supporting the latter, although it is possible they just prefer to tank using singles matches so it doesn't look as suspicious.  It is also possible the 3/20 doubles result was a fluke in some way due to an opponent having a bad day or just the way the algorithm works in some circumstances and so their results don't really vary that much.

What do you think?