We love talking about sandbaggers around here. Check that, we obsess about sandbaggers. But how big of a problem is it really? Since tennisleaguestats.com has a nice set of data that I can use, I decided to see if I can deduce sandbaggers from this dataset. I chose data from 4 different areas (Northwest Washington, Baltimore, Manhattan, and Dallas - sorry, I only looked at men). Selected all people who self-rated (if you are computer rated, by definition, you are correctly rated - sure, some people can "manage" their ratings, but that is really difficult to do over time) and see if the have tendencies to under-rate or over-rate themselves. I compared the ratings level these self-raters played in 2013 against what TLS determined their proper ratings should be. And here are the results. In general, people select the correct ratings for themselves. Within all the areas that I looked at 64% of the people ended up with TLS level equaling their current USTA level. If anything, people have tendencies to over-rate themselves. 27% ended up with TLS level that is lower than their current USTA level. Out of all of these people (785 total) only 68 (8.7%) people can be considered sandbaggers. If you eliminate those who were within .1 of their correct rating, that number gets down to only 42 (5.4%). I think you can safely deduce that sandbagging is not pervasive and certainly not a huge problem in USTA leagues in general.