On/Off Rating
The difference between a team's net rating when a player is on the floor and when he is off. A read on a player's actual effect on the team.
What On/Off Rating measures
Box-score stats tell you what a player does. On/Off tells you what happens to the team because of him. A player who averages 8 points and 4 assists can look modest, but if the team is +12 per 100 possessions with him on and -5 with him off, he may be the most important man on the roster. On/Off cuts through role, usage and box-score noise to ask the most basic question in the sport: is this team better or worse with him out there?
How On/Off Rating is calculated
ON/OFF = Team Net Rating with the player on the floor − Team Net Rating with him off it
The catch
On/Off is very sensitive to small samples
A player with 400 minutes has seen maybe 600 to 700 possessions on the floor. Enough for a rough signal, not a verdict. Who he played with, who he played against, and when he sat can all bend the number. It steadies above 1,000 minutes.
It mixes a player up with his lineup
A player on a dominant team shows a positive On/Off even if he adds little, because his teammates carry the load. A player on a weak team can show a flat or negative one while playing well, because the group cannot hold the lead when he rests. Always read On/Off next to the quality of his teammates and lineups.
Seen in a game
On/Off often surfaces hidden value. Backup guards who set the tempo, versatile defenders who cover several positions, and steady bigs who anchor a rotation can all show strongly positive On/Off numbers on modest box scores. The reverse happens too: a high-usage scorer who dominates the ball can show a flat On/Off, because his scoring comes at the cost of everyone else's rhythm. The number rewards the players who make the four around them better.
Common questions
- What is on/off rating?
On/off rating compares how a team performs with a player on the floor versus on the bench. It captures impact that never shows up in the box score, like spacing, screening and defensive attention.
- How is on/off rating calculated?
Take the team's net rating while the player is on court and subtract its net rating while he sits. A positive number means the team is better with him out there.
- Why can on/off rating be misleading?
It depends heavily on which teammates a player shares the floor with and on sample size. A backup can look great next to starters. Use on/off as a clue, confirmed against a full season, not proof on its own.
