For some odd reason, the gold standard for determining player performance in the NBA is the Player Efficiency Rating (PER). It was developed a few years back by John Hollinger of ESPN. He calls it "a rating of a player's per-minute productivity." I've never been a big fan of PER, or John Hollinger for that matter (He's a Wizards Hater).
To start with, PER does not account for a player's defensive performance. According to Hollinger's PER introduction article, "PER is not the final, once-and-for-all evaluation of a player's accomplishments during the season. This is especially true for defensive specialists...who don't get many blocks or steals." This is utterly baffling to me. Why not adjust your methodology to account for defensive statistics? The formula is already complicated enough that adding a few more variables shouldn't be that big of a deal. I don't see how Hollinger can claim PER as an adequate way to obtain a player's level of productivity. One cannot measure a player's overall efficiency without incorporating offensive and defensive productivity (despite popular belief, defense does count for something in the NBA).
Oh, by the way, the very long PER formula can be found
here, if you want to bore yourself. I will not discuss Hollinger's PER statistic any further due to its convoluted and bias nature towards offensive performance.
I have developed a basic statistical methodology for calculating the net offensive and defensive performance of an NBA player. This new statistic, simple player performance rating (sPPR), will measure the current effectiveness of an NBA player in a given season. Four offensive and four defensive primary statistics recorded by the NBA will be used to determine sPPR:
Four Offensive StatisticsTrue Shooting % (TS%)
Points Per Game (PPG)
Assists Per Game (APG)
Defensive Rebounds Per Game (DRPG)
Four Defensive Statistics UsedSteals Per Game (SPG)
Offensive Rebounds Per Game (ORPG)
Blocks Per Game (BPG)
Turnovers Per Game (TPG)
To simplify the calculation for sPPR, the eight offensive and defensive statistics listed above were condensed into five statistical factors:
Shooting Efficiency (1) - max: 100%, min: 0% - player receives one tally per level* of TS% achieved
*Levels - 35, 40, 45, 50, 53, 57, 60, 63, 65, 68
Scoring (2) - max: 30, min: 0 - player's PPG is used
Passing (3) - max: 10, min: 0 - player's APG is used
Rebounding (4) - max: 10, min: 0 - player's DRPG is used
Intangibles (5) - max: 8, min: 0 - player's SPG plus ORPG plus BPG minus TPG is used
sPPR Calculation Steps1. Each factor's tally total is divided by its corresponding maximum. Multiply factor 4's result by 1.5 to create a fair baseline between guards and forwards/centers.
(creates an equilibrium between all positions) 2. Add up the results of step one.
3. Divide the result of step two by the total number of factors (5).
4. Divide the result of step three by player's team pace.
5. Multiply result of step four by 100 to achieve sPPR.
Example: Chris Paul (as of March 3rd, 2010)
Step 1 Factor 1 = 50.97% =
4.0 talliesFactor 2 = 20.4 =
20.4 talliesFactor 3 = 11.2 =
11.2 talliesFactor 4 = 4.1 = 4.1 tallies x 1.5 =
6.15 talliesFactor 5 = 2.3+0.5+0.2-2.5 =
0.5 tallies
Step 240+68+112+(34*1.5)+6 =
316.4Step 3 316.4/5 =
63.6%Step 40.632833/94.8 =
0.006675Step 5
sPPR = 0.006675 x 100 = 0.667546 or 66.8%
So what does all of this mean? Based on simple statistics (sPPR), Chris Paul is second most effective player in the NBA - only 1.6 percentage points behind LeBron James.
Top 10 sPPR (as of March 10th, 2010)
I realize that sPPR may not be the most statistically sound way to measure NBA player performance since statistics like usages rates and minutes played are ignored, but its better than trying to make sense of PER's calculation. I think you need a Ph.D. in statistics to
understand decipher the PER methodology, whereas the sPPR formula should make sense to everybody because its methodology is based on common sense and simple terminology. Based on my findings, I believe sPPR is a more accurate representation of an NBA player's combined offensive and defensive prowess.
The complete working file with all of the NBA player statistics and sPPR calculation is located here. A results file with a comparison of Top 10 between PER and sPPR is listed here. An updated copy will be kept in the Proposition Documents page and on the right side toolbar.