The Player Efficiency Rating is ESPN Insider writer John Hollinger

John Hollinger

John Hollinger is an analyst and writer for ESPN. He primarily covers the NBA. Hollinger grew up in Mahwah, New Jersey and is a 1993 graduate of the University of Virginia....

's all-in-one basketball

Basketball

Basketball is a team sport in which two teams of five players try to score points by throwing or "shooting" a ball through the top of a basketball hoop while following a set of rules...

 rating, which attempts to boil down all of a player's contributions into one number. Using a detailed formula, Hollinger developed a system that rates every player's statistical performance.

Introduction

PER strives to measure a player's per-minute performance, while adjusting for pace. A league-average PER is always 15.00, which permits comparisons of player performance across seasons.

PER takes into account positive accomplishments, such as field goals, free throws, 3-pointers, assists, rebounds, blocks and steals, and negative ones, such as missed shots, turnovers and personal fouls. The formula adds positive stats and subtracts negative ones through a statistical point value system. The rating for each player is then adjusted to a per-minute basis so that, for example, substitutes can be compared with starters in playing time debates. It is also adjusted for the team's pace. In the end, one number sums up the players' statistical accomplishments for that season.

PER's Relationship to Baseball "Sabermetrics"

Hollinger's work has benefitted from the observations of Sabermetric baseball analysts, such as Bill James

Bill James

George William “Bill” James is a baseball writer, historian, and statistician whose work has been widely influential. Since 1977, James has written more than two dozen books devoted to baseball history and statistics...

. One of the primary observations is that traditional counting statistics in baseball, like runs batted in and wins, are not reliable indicator's of a player's value. For example, runs batted in is highly dependent upon opportunities created by a player's teammates. PER extends this critique of counting statistics to basketball, noting that a player's opportunities to accumulate statistics is dependent upon the number of minutes he plays as well as the pace of the game.

Problems With PER

PER largely measures offensive performance. Hollinger freely admits that two of the defensive statistics it incorporates -- blocks and steals -- can produce a distorted picture of a player's value and that PER is not a reliable measure of a player's defensive acumen. For example, Bruce Bowen

Bruce Bowen

Bruce Bowen Jr. is a retired American professional basketball player. The 6'7", 200-lb. Bowen played small forward and graduated from Edison High School and Cal State Fullerton...

, widely regarded as one of the best defenders in the NBA (at least through the 2006-07 season), has routinely posted single-digit PERs.

"Bear in mind that this rating is not the final, once-and-for-all answer for a player's accomplishments during the season. This is especially true for players such as Bruce Bowen and Trenton Hassell who are defensive specialists but don't get many blocks or steals."

Neither PER nor per-game statistics take into account such intangible elements as competitive drive, leadership, durability, conditioning, hustle, or WIM (wanting it more), largely because there is no real way to quantitatively measure these things.

In addition, some have argued that PER gives undue weight to a player's contribution in limited minutes, or against a team's second unit, and it undervalues players who have enough diversity in their game to play starter's minutes.

Lastly, PER rewards inefficient shooting. To quote Dave Berri, the author of The Wages of Wins:

"Hollinger argues that each two point field goal made is worth about 1.65 points. A three point field goal made is worth 2.65 points. A missed field goal, though, costs a team 0.72 points. Given these values, with a bit of math we can show that a player will break even on his two point field goal attempts if he hits on 30.4% of these shots. On three pointers the break-even point is 21.4%. If a player exceeds these thresholds, and virtually every NBA player does so with respect to two-point shots, the more he shoots the higher his value in PERs. So a player can be an inefficient scorer and simply inflate his value by taking a large number of shots."

Problems with PER Projections

The projections are built by looking at comparable players at the same age and how their stats changed in the following season. For players in most age brackets, this is extremely reliable, but there have been so few players to turn pro out of high school in the past two decades that there is a very small sample to work with. While some players who have come out of high school have shown a lot of promise in their future years, many have floundered and never quite reached their full potential.

Reference guide

Hollinger has set up PER so that the league average, every season, is 15.00, which produces sort of a handy reference guide:

• A Year For the Ages: 35.0
• Runaway MVP Candidate: 30.0
• Strong MVP Candidate: 27.5
• Weak MVP Candidate: 25.0
• Bona fide All-Star: 22.5
• Borderline All-Star: 20.0
• Solid 2nd option: 18.0
• 3rd Banana: 16.5
• Pretty good player: 15.0
• In the rotation: 13.0
• Scrounging for minutes: 11.0
• Definitely renting: 9.0
• The Next Stop: DLeague 5.0

Only 15 times has a player posted a season efficiency rating over 30.0. All of them are between 30.23 and 31.84. Michael Jordan leads with four 30+ seasons, with Shaquille O'Neal and Wilt Chamberlain having accomplished three each, LeBron James having accomplished it twice, and David Robinson, Dwyane Wade and Tracy McGrady having accomplished one each. The 2008-2009 season was unique in that it was the only season in which more than one player (LeBron James and Dwyane Wade, with Chris Paul just missing the cut with a PER of 29.96) posted efficiency ratings of over 30.0.

Career PER leaders

(Courtesy of Basketball-Reference.com)

Rank	Player	PER
1.	Michael Jordan*	27.91
2.	LeBron James^	26.86
3.	Shaquille O'Neal	26.59
4.	David Robinson*	26.18
5.	Wilt Chamberlain*	26.13
6.	Dwyane Wade^	25.67
7.	Bob Pettit*	25.37
8.	Tim Duncan^	25.02
9.	Neil Johnston*	24.72
10.	Charles Barkley*	24.63
11.	Kareem Abdul-Jabbar*	24.58
12.	Magic Johnson*	24.11
13.	Karl Malone*	23.90
14.	Dirk Nowitzki^	23.76
15.	Kevin Garnett^	23.59
16.	Hakeem Olajuwon*	23.59
17.	Kobe Bryant^	23.50
18.	Larry Bird*	23.50
19.	Oscar Robertson*	23.17
20.	Yao Ming	23.04
21.	Jerry West*	22.90
22.	Tracy McGrady^	22.81
23.	Elgin Baylor*	22.70
24.	Amare Stoudemire^	22.57
25.	Moses Malone*	22.31
26.	Julius Erving*	21.97
27.	Dolph Schayes*	21.96
28.	Pau Gasol^	21.89
29.	John Stockton*	21.83
30.	Elton Brand^	21.80
31.	George Gervin*	21.74
32.	Dwight Howard^	21.69
33.	Bob Lanier*	21.69
34.	Clyde Lovellette*	21.67
35.	Manu Ginobili^	21.65
36.	Dominique Wilkins*	21.56
37.	Adrian Dantley*	21.51
38.	Harry Gallatin*	21.49
39.	Chris Bosh^	21.28
40.	Alonzo Mourning	21.24
41.	Arvydas Sabonis*	21.20
42.	Vince Carter^	21.09
43.	Clyde Drexler*	21.07
44.	Patrick Ewing*	21.01
45.	Dan Issel*	20.99
46.	Chris Webber	20.94
47.	Allen Iverson^	20.92
48.	Carlos Boozer^	20.81
49.	Paul Pierce^	20.80
50.	John Drew	20.74

* = Hall of Fame
^ = Active

Calculation

All calculations begin with what is called unadjusted PER (uPER). The formula is:

Where

• ,
• ,
• .

Once uPER is calculated, it must be adjusted for team pace and normalized to the league to become PER:



This final step takes away the advantage held by players whose teams play a fastbreak

Fastbreak

Fast break is an offensive strategy in basketball. In a fast break, a team attempts to move the ball up court and into scoring position as quickly as possible, so that the defense is outnumbered and does not have time to set up. There are various styles of the fast break and the fast break attack...

style (and therefore have more possessions and more opportunities to do things on offense), and then sets the league average to 15.00.

Also note that it is impossible to calculate PER (at least in the conventional manner described above) for NBA seasons prior to 1978, as the league did not keep track of turnovers before that year.

External links

• CREZ Basketball Systems Inc., Software to score your own basketball games and view PER player and lineup statistics
• An in-depth description of how to calculate PER
• Hollinger's articles at SI
• Basketball-Reference.com, Historical NBA statistical site (includes PER)
• KnickerBlogger.net
• ESPN.com Insider (subscription service)