Player efficiency rating

The player efficiency rating (PER) is John Hollinger's all-in-one basketball 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.[1]

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 accomplishments, such as field goals, free throws, 3-pointers, assists, rebounds, blocks and steals, and negative results, 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.

Relationship to baseball sabermetrics

Hollinger's work has benefitted from the observations of sabermetric baseball analysts, such as Bill James. One of the primary observations is that traditional counting statistics in baseball, like runs batted in and wins, are not reliable indicators 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 are dependent upon the number of minutes played 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 (which was not tracked as an official stat until 1973)—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, widely regarded as one of the best defenders in the NBA through the 2006–07 season, 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.

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.

PER has been said to reward 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.

Hollinger responded via a post on ESPN's TrueHoop blog:

Berri leads off with a huge misunderstanding of PER—that the credits and debits it gives for making and missing shots equate to a “break-even” shooting mark of 30.4% on 2-point shots. He made this assumption because he forgot that PER is calibrated against the rest of the league at the end of the formula.

Actually, if we took a player that was completely average in every other respect for the 2006–07 season—rebounds, free throws, assists, turnovers, etc.—and gave him a league-average rate of shots, and all of them were 2-pointers, and he shot 30.4%, he'd end up with a PER of 7.18. As long-time PER fans know, that would make him considerably worse than nearly every player in the league.

To end up with a league-average PER of 15.00, the actual break-even mark in this case is 48.5%, which is exactly what the league average is on 2-point shots this season.

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:[2]

All-time great season 35.0+
Runaway MVP candidate 30.0–35.0
Strong MVP candidate 27.5–30.0
Weak MVP candidate 25.0–27.5
Definite All-Star 22.5–25.0
Borderline All-Star 20.0–22.5
Second offensive option 18.0–20.0
Third offensive option 16.5–18.0
Slightly above-average player 15.0–16.5
Rotation player 13.0–15.0
Non-rotation player 11.0–13.0
Fringe roster player 9.0–11.0
Player who won't stick in the league 0–9.0

Only 21 times has a player posted a season efficiency rating over 30.0 (with more than 15 games played in that season), with the highest score being 31.82 (Wilt Chamberlain). Michael Jordan and LeBron James lead with four 30+ seasons, with Shaquille O'Neal and Wilt Chamberlain having accomplished three each, Anthony Davis having accomplished two, and David Robinson, Tracy McGrady, Dwyane Wade, Chris Paul, Stephen Curry, Russell Westbrook, Giannis Antetokounmpo, and James Harden [3] having accomplished one each.

Career PER leaders

as of 5 March 2020[4]

RankPlayerPER
1.Michael Jordan*27.91
2.Anthony Davis27.52
3.LeBron James27.51
4.Shaquille O'Neal*26.43
5.David Robinson*26.18
6.Wilt Chamberlain*26.13
7.Bob Pettit*25.34
8.Kevin Durant25.20
9.Chris Paul25.09
10.James Harden24.75
11.Neil Johnston*24.69
12.Charles Barkley*24.63
13.Kareem Abdul-Jabbar*24.58
14.Tim Duncan24.22
15.Magic Johnson*24.11
16.Karl Malone*23.90
17.Stephen Curry23.83
18.Hakeem Olajuwon*23.59
19.Julius Erving*23.58
20.Russell Westbrook23.54
21.Larry Bird*23.50
22.Dwyane Wade23.48
23.Oscar Robertson*23.17
24.Yao Ming*23.02
25.Kawhi Leonard23.00
26.Giannis Antetokounmpo22.91
27.Kobe Bryant22.90
28.Jerry West*22.89
29.Elgin Baylor*22.69
30.Kevin Garnett22.66
31.Dirk Nowitzki22.44
32.DeMarcus Cousins22.40
33.Kyrie Irving22.25
34.Tracy McGrady*22.13
35.Andre Drummond22.06
36.Blake Griffin22.00
37.Moses Malone*22.00
38.Dolph Schayes*21.98
39.Damian Lillard21.89
40.John Stockton*21.83
41.Amar'e Stoudemire21.82
42.Bob Lanier*21.69
43.Kevin Love21.59
44.Dominique Wilkins*21.56
45.Clyde Lovellette*21.55
46.Dwight Howard21.50
47.Adrian Dantley*21.51
48.Harry Gallatin*21.48
49.Artis Gilmore*21.40
50.George Gervin*21.38
51.Pau Gasol21.37
51.Dan Issel*21.37
53.Alonzo Mourning*21.24
54.Clyde Drexler*21.07
55.Rick Barry*21.04
56.Patrick Ewing*21.01
57.Chris Webber20.94
58.Allen Iverson*20.92
59.LaMarcus Aldridge20.84
60.John Drew20.74
61.Bob McAdoo*20.73
62.Kevin Johnson20.70
63.Al Jefferson20.56
64.Chris Bosh20.56
65.Elton Brand20.51
66.George Yardley*20.51
67.Nikola Vučević20.42
68.Ed Macauley*20.39
69.Jimmy Butler20.29
70.Manu Ginóbili20.22
71.Larry Foust20.19
72.Marques Johnson20.11
72.John Brisker20.11
74.Greg Monroe20.08
74.Mel Daniels*20.08
76.George McGinnis*20.05
77.Billy Cunningham*20.04
78.Kevin McHale*20.02
79.Carmelo Anthony19.96
80.Steve Nash*19.95
81.Larry Nance19.92
82.David Thompson*19.91
83.Connie Hawkins*19.89
84.Alex English*19.87
85.Walt Bellamy*19.84
85.Isaiah Thomas19.81
87.Cliff Hagan*19.80
88.Bob Cousy*19.76
89.Paul Pierce19.73
90.Terrell Brandon19.69
91.Paul Arizin*19.66
92.Mark Price19.62
93.John Beasley19.59
94.Gilbert Arenas19.57
93.Brook Lopez19.54
96.Sam Cassell19.48
96.Michael Redd19.48
98.Carlos Boozer19.46
99.Kemba Walker19.45
100.John Wall19.43
100.Paul Westphal*19.43

Active players are listed in bold. * Indicates member of the Hall of Fame.

PER since 1951–52

Career PER – Michael Jordan vs. LeBron James

Prior to the 2013–14 season, LeBron James was on the verge of surpassing Michael Jordan's career PER to take the number one spot.[5][6] (even if James should take the number one spot from Jordan, he is still mid-career. As the metric is averaged over the length of a player's entire career a decrease in efficiency later in his career means a player can move down in the ranking. For example, Jordan's PER took a big hit in the final two years of his career when he returned to the game with the Washington Wizards, posting 20.7 in his penultimate season and 19.3 in his final season, compared to his career high of 31.7. Jordan's PER was 29.1 without accounting for his Wizards years.).[7] The debate was intensified on 1 October 2013, with Jordan stating that he would have liked to have played against LeBron, and believes he would have won a one-on-one encounter.[8] As a result, many news features[9][10][11] are focusing on comparing the two players, with some using the PER metric to compare the two players. At the conclusion of the 2012–13 NBA season Miami Heat head coach, Erik Spoelstra, stated that comparing players from different generations is the equivalent to comparing "apples and oranges. You’ll never be able to tell [how James stacks up to Jordan or Magic Johnson] because they didn't play against each other. The game is different now than when it was played in the 1980s or even before that".[12]

Players from different NBA generations and Career PER

Comparing players from different generations using PER presents several problems, this is primarily due to the rule changes and the changes in statistical data collected from different eras (although many other factors could be taken into consideration, even down to the increased sample size as the NBA grew through incorporating more teams). Some of the more important rule changes that should be considered include; some of the players on this list played before the three-point shot, blocks, and steals stats were officially recorded (Wilt Chamberlain, Bill Russell, etc.). Blocked shots and steals were first officially recorded in the NBA during the 1973–74 season. The three-point shot entered the league in 1979–80 season. During the 1990s and 2000s numerous rule changes were incorporated, the "three point foul" and "clear path" rules were both introduced in the 1995–96 season with the effect of increasing the number of free throws, hand-checking (the amount of contact a defender may make with an opposing player) was banned in 1994 and the use of elbows was banned in 1997 (both rules had seen various degrees of limitation by earlier rule changes) although neither was fully implemented until 2004. The 2004 rule changes, which also included calling the defensive 3 second rule ("[...] a defensive player may not station himself in the key area longer than three seconds"—a longstanding rule which had been ignored by referees) had a major effect, opening up the game and allowing a more free-flowing offense; it encouraged aggressive inside attack based plays (to draw fouls), and has increased the number of fouls given when contact is made on players who drive to the basket.[13] Former ABA and NBA Coach Larry Brown is quoted as saying "The college game is much more physical (than the NBA) [...] I always tease Michael (Jordan), if he played today, he'd average 50".[14]

Calculation

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

When multiplied out and refactored, the equation above becomes:

Where

  • ,
  • ,
  • .

With

  • tm, the prefix, indicating of team rather than of player;
  • lg, the prefix, indicating of league rather than of player;
  • min for number of minutes played;
  • 3P for number of three-point field goals made;
  • FG for number of field goals made;
  • FT for number of free throws made;
  • VOP for value of possession (but in reference to the league, in this instance);
  • RB for number of rebounds: ORB for offensive, DRB for defensive, TRB for (total) combined, RBP for percentage of offensive or defensive;
  • others being outlined in basketball statistics.

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 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 among other advanced statistics before that year.

References
  1. Basketball Reference https://www.basketball-reference.com/about/per.html. Retrieved 5 September 2013. Missing or empty |title= (help)
  2. "Hardwood Paroxysm". Archived from the original on 10 September 2017. Retrieved 16 April 2017.
  3. https://www.basketball-reference.com/play-index/psl_finder.cgi?request=1&match=single&type=totals&per_minute_base=36&per_poss_base=100&season_start=1&season_end=-1&lg_id=NBA&age_min=0&age_max=99&is_playoffs=N&height_min=0&height_max=99&birth_country_is=Y&as_comp=gt&as_val=0&pos_is_g=Y&pos_is_gf=Y&pos_is_f=Y&pos_is_fg=Y&pos_is_fc=Y&pos_is_c=Y&pos_is_cf=Y&c1stat=per&c1comp=gt&c1val=29.95&c2stat=g&c2comp=gt&c2val=20&order_by=per
  4. "NBA & ABA Career Leaders and Records for Player Efficiency Rating". Basketball Reference. Retrieved 19 February 2019.
  5. ESPN.com - "2012-13 Hollinger NBA Player Statistics - All Players" - Accessed 6 October 2013
  6. Basketball Reference, "LeBron James". Accessed 6 October 2013
  7. Basketball Reference, "Michael Jordan" - Accessed 6 October 2013.
  8. NBA.com - "Jordan proclaims he could beat LeBron in prime". Accessed 6 October 2013.
  9. Busfield, Steve. The Guardian, Michael Jordan vs LeBron James: who is better?" Accessed 6 October 2013
  10. Helin, Kurt. NBCsports.com "LeBron says he wants to be greatest of all time, still "far away from it". Accessed 6 October 2013
  11. Lariviere, David. Forbes, "LeBron James Will Eventually Top Michael Jordan As Basketball's Greatest Player". Accessed 6 October 2013.
  12. Golliver, Ben. Sports Illustrated, "Spoelstra: Comparing LeBron to Jordan is impossible because 'game is different now' Archived 11 October 2013 at the Wayback Machine" - Accessed 6 October 2013
  13. NBA.com - NBA Rules History. Accessed 6 October 2013.
  14. Aldridge, David. NBA.com - Rules changes have affected defensive philosophies. Accessed 6 October 2013
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