How many possessions does an NBA lineup need to play before we are confident it is good?

Plus-minus data is at the bedrock of a lot of thoughtful NBA analysis. If I tell you that the Celtics have outscored their opponents by 153 points in the 350 minutes that Jaylen Brown, Marcus Smart, and Al Horford have shared the court this season (per basketball reference), then you might reasonably conclude that these players are doing something right when they are playing together. At the end of the day, a valuable lineup needs to have a good raw plus-minus score (points scores minus opponents points scored). If a lineup of players is, over time, consistently outscored by the opposing lineups then this lineup cannot be considered effective.

The key question is what exactly does over time mean? One of the problems with looking at raw-plus minus scores for lineups are that they are heavily effected by small sample sizes. Especially early in the season, a good game or two can make an entirely average lineup look like world beaters.

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Usage and True Shooting Tracker

I made a web app that allows you to see how the players on each team rate according to usage and true shooting. You can quickly get a sense for how players compare to one another and can sort by team or position.  The points are also sized and colored according to a player’s offensive rating, so you can see how much better (or worse) the team’s offense has been while they are on the court. The app will be updated as the season progresses so you can always see current stats.

As a bit of explanation, usage percentage is a measure of the percentage of possessions that a player “uses up” when they are on the floor. True shooting percentage is a measure of how efficient a player is shooting the ball.  It takes into account free throw shooting and the fact that 3’s are worth more than 2’s. High usage, high true shooting players are obviously really valuable.

Try it out!

 

(All data is courtesy of basketball-reference.com)