PLAYER IMPACT PLUS-MINUS
Player Impact Plus-Minus is a metric that combines traditional boxscore value with luck-adjusted on/off player data to estimate how much value a player adds to their team.
Luck-adjusted data, developed by Nathan Walker, is used to adjusted for factors that are out of an individual team or player’s control. For instance, free throw shooting and three point shooting can cause wide variance in the specific ratings, but in studies it has been shown that teams and players have limited control over makes or misses. Another example is adjusting for rebounding and turnovers to attempt to limit the noise from the final values.
The boxscore component is calculated off a regression from a 15-year RAPM sample. Especially on offense, there is real value to be found in the traditional boxscore. Combining that with more advanced play by play data, PIPM is able to see who is adding value that the boxscore is unable to capture.