How PER is CalculatedThe goal of PER is to assign a single number to a player, which indicates their effectiveness on the court. This is done by examining all the official statistics kept by the NBA including both positive statistics, such as field goals made and assists, as well as negative statistics, such as turnovers.
Each statistic is assigned a value used to weight the contribution of that statistic to the PER formula. This is done because not all statistical categories are equally important. For example, field goals made are weighted more heavily than assists. Assists are important, but not as important as shots made, since they are the desired end result of any possession. Research has been done by Hollinger and other statisticians in an attempt to determine the exact relative importance (numerically) of each statistic.
The calculation goes further by using per-minute statistics, rather than raw totals or per-game numbers. Per-minute statistics are far more meaningful in representing a player's productivity than any of the aforementioned methods. For example, let's compare a player (A) who scores 14 points per game and plays 20 minutes per game, to a player (B) who scores 15 points per game and plays 35 minutes per game. Player B scores more per game than player A, but because he needs to play many more minutes than player A to accomplish this, player A is actually the more productive player in the time he's on the court.
Another element that increases the accuracy of PER is that all numbers are adjusted by the "pace" of each individual team. A team that plays at a much higher pace (shots per minute, for example) gives its players more of an opportunity to put up numbers, but that doesn't mean that player is better, or playing more effectively than those on slower-paced teams.
How to Interpret the PER
The way the PER formula is constructed, the PER of an average NBA player is always 15. The following is a breakdown of what various PER values indicate:
All-time great season: 35+
Hands-down MVP: 30-35
Strong MVP candidate: 27.5-30
Long-shot MVP candidate: 25-27.5
Definite All-Star: 22.5-25
Borderline All-Star: 20-22.5
Second offensive option: 18-20
Third offensive option: 16.5-18
Slightly above-average player: 15-16.5
Rotation player: 13-15
Non-rotation player: 11-13
Fringe roster player: 9-11
Player who won't stick in the league: 5-9
The all-time leader in career NBA PER is Michael Jordan with 27.91 over his career. Other players in the all-time top ten include Shaquille O'Neal (26.43), David Robinson (26.18), Wilt Chamberlain (26.13) and Bob Pettit (25.37).
Benefits of the PER Statistic
PER is a huge step up from looking at standard boxscore statistics. It is much more detailed and accurate than anything one can do with raw statistical totals or per-game numbers.
Negatives of the PER Statistic
The one major weakness in the original PER concept is lack of consideration for defense. Yes, there are blocked shots and steals, but the formula doesn't account in any way for guys who play great individual or team defense. A solution to this was found by Roland Beech of 82games, who came up with a way to estimate a player's defensive prowess by looking at the PER of the players he defended during the season. This addition made PER an even more powerful analytical tool.