RAPM in the NBA

Create your own RAPM analysis.

Do you know what RAPM means?

It’s regularized adjusted plus minus. You might have heard of Plus Minus metric (+/-) in the NBA. It’s a summary stat that should address the impact of each player during a game. Positive is good, negative is bad. It depends on the performance of the team while the player was on court.

It seems good, and it is, but has a lot of flaws. Specially when you factor in that some player play much more than others, and in particular, with different teammates.

Each team is different, and inside each team, the rotation is different. If you score a lot during garbage time, against the worst roster of your opponent… plus minus doesn’t know that.

RAPM comes to fix that, or try. In summary, it takes into account who is on the court at the same time, both teammates and opponents. So, if you always play along Lebron James maybe you are not the one having the greatest impact on the court..

It’s super interesting and a good exercise to do if you want to add something to your portfolio and bag of tricks.

I’ve found this site that has a nice dataset to do it yourself (and more data even for other sports!).

If you want a more in depth explanation on how to do this, you can follow this series of posts. The author worked for several teams in the NBA, just scroll around to find the rest of the parts!