Hockey stat, with a twist, useful in NBA, too
Since the NHL has no use for plus-minus this season, NBA stat fiends should borrow the tool. But in basketball, plus-minus is best appreciated with a slight twist.
It's a powerful tool with a simple premise: Add all the points the team scores when a player is on the court, and subtract all the points the team allows when he is on the court. Subtract the latter from the former, and you end up with the player's "plus-minus" how many points better or worse (i.e., plus or minus) the team is with that man on the court.
As that dejected lot known as hockey fans can tell you, NHL teams have used plus-minus for several years to figure out which players have the greatest impact. In a sport where scoring is so infrequent and defensive evaluations are so difficult, plus-minus is both easy to track and, once you know how to interpret it, highly informative.
For years, basketball aficionados hoped for something similar, but because scoring is so much more frequent in basketball, tracking plus-minus for every player over a full season was an incredibly laborious process.
Fortunately, the information age has arrived, and with it has come folks like those at 82games.com. They've computerized all the info in play-by-play sheets and churned out plus-minus marks for every player in the league.
As hockey fans already know, plus-minus by itself isn't very telling. The leaders in this category are all the players on the best clubs, while those at the bottom saw a lot of minutes on awful teams. In other words, the quality of a player's teammates does more to determine his plus-minus than the quality of the player himself.
Nonetheless, we can glean useful information by comparing a player's plus-minus when he's on the court against his plus-minus when he's off it.