After introducing RAPM for college basketball, I'm very excited to share my newest innovation. College RAPM now incorporates a Bayesian prior!

Even though vanilla RAPM performance was much better than I had anticipated, by adding a Bayesian adjustment we are able to increase stabilization and improve performance even further.

Bayesian Adjusted RAPM

For those who are unfamiliar, Bayesian Adjusted RAPM is a variation of RAPM where each player is assigned a prior based on additional information (e.g. playing time, team strength, box score stats, previous year performance, high school rank). Rather than RAPM regressing players towards an overall average player value, instead everyone is regressed towards their own player specific prior.

There are a number of different ways one can construct and weight a Bayesian prior. In order to evaluate different options, it is important to define a goal, as the ideal prior can vary based on your objective. To guide my evaluation process, I considered the following goals:

Improve validity - measured through out of sample performance

- measured through out of sample performance Improve reliability - measured by year to year player correlation

- measured by year to year player correlation Reduce the effects of collinearity - distinguish between players who always play together

- distinguish between players who always play together Reduce the effects of small samples - distinguish between players with a small number of possessions

- distinguish between players with a small number of possessions Keep RAPM pure - having RAPM be dominated by an overfit box score prior in order to minimize the error is not the goal

After extensive tinkering, I settled on a blended prior which equally weights the following:

Team Prior Incorporates the strength of a players team, the percentage of possessions a player played, and the interaction between the two

Allows RAPM to regress low minute players to different values depending on team quality (e.g. a low minute bench player is likely better on UNC than UNC-Wilmington) Box Score Prior Incorporates box score counting stats, rate adjusted per possession

No interaction terms were used, to slightly weaken the fit of the prior and help avoid challenges of outlier box score stats

Allows RAPM to better differentiate the impact of players on teams with limited lineup variation

Results

Download complete RAPM results (for 2010-2019 seasons):

NBA Draft Picks

Select your favorite draft class to see how RAPM viewed future NBA players (in their final college season):

2018 2017 2016 2015 2014 2013 2012 2011 2010

Top Players

Check out the top-rated players in O-RAPM, D-RAPM, and overall RAPM.

Multi-Year 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 RAPM O-RAPM D-RAPM

BPM Comparison

See which players stand out the most from their box score stats by comparing to top players in BPM:

2019 2018 2017 2016 2015 2014 2013 2012 2011 BPM OBPM DBPM RAPM O-RAPM D-RAPM

Teams

Select your favorite team to see if RAPM results align with your expectations: