Plus/minus can be a sign of a player's impact, or it can be a sign of how poor his backup is. It's incredibly noisy, and it's not unusual for who a player's on the court with to have a large effect on that player's numbers. Also, you talk about a season being an incredibly large sample size, but I think the prevailing thought on those numbers is that you'd have to see a player's numbers over a number of seasons before you could draw any meaningful conclusions.
Plus/minus does not talk about a player's backup at all. That can be the problem with On/Off stats (how a team performs when a player is off the court vs. on). +/- describes how the team performed on the scoreboard with a given player on the court. It is noisy, in that it ascribes to a player things that the player cannot control. Primarily, what it ascribes to a player is who is on the court at the same time -- both his own teammates as well as opponents. If you are a good player playing with mostly backups, your +/- will suffer relative to your abilities. Likewise, if you are not good and playing with good players, it will look better than it is. Similarly, if you are typically on the court the same time as your opponents best players, your +/- will be deflated, whereas if you are on the court again backups or benchwarmers, it will increase. When people are talking about "Real Plus-Minus", they are talking about a stat that
attempts to cut through that noise on a season-long basis.
All stats have their flaws, and most stats have their uses. Traditional +/- use is a quick indicator that a player's on-court contributions in a given game
might have been more or less than they appear according to other traditional box score stats, such as points/shooting, rebounds, and assists. If you see someone has a bad game in boxscore stats but has a high +/-, maybe see how well opponents he was defending shot, if he forced turnovers that don't show up as steals (forcing players out of bounds, for instance), harassed ballhandlers at the start of possessions to force teams into bad shots and/or kept the ball out of the best playmaker's hands, etc. On offense, maybe this player did not get credit for assists, but still got the ball frequently in good places for his teammates to make is , by commanding double teams and passing out of them, or requiring help defenders on penetration which led to easy weak-side rebounds and putbacks.
Is +/- the best stat out there? No. Can it be useful? Yes.
Topic: Vegas Summer League: Game 3 Celtics (2-0) vs Heat (1-1) 7/14/15 (Read 58202 times)