Player Efficiency Rating (PER) is an advanced NBA statistic that sums up a player’s statistical accomplishments in a single number.
Developed by John Hollinger, PER has become a popular tool for comparing players across the league.
What is Player Efficiency Rating (PER)?
Player Efficiency Rating (PER) is an intends to measure a player’s per-minute performance, normalized so that the league average is 15.
The aim of PER is to boil down all of a player’s contributions into one number.
Using a detailed formula that adjusts for the pace of the game, PER takes into account accomplishments such as points, rebounds, assists, steals, and blocks, and also considers negative outcomes like missed shots, turnovers, and personal fouls.
Here are the top players in NBA history in PER ratings.
The Formula for PER
The calculation of PER is complex, involving many coefficients to balance each statistic.
Basic Formula Components for PER:
- uPER (Unadjusted PER):
- Positive Contributions: Points, field goals made, free throws made, 3-point field goals made, assists, rebounds, blocks, and steals are all factored in positively.
- Negative Contributions: Missed field goals, missed free throws, and turnovers negatively affect the rating.
- Adjustments:
- Pace Adjustment: PER is adjusted for the team’s pace to normalize a player’s ratings through an adjustment factor so that performance comparisons can be made across different team styles of play.
- League Adjustment: Normalizes the final PER to a league average of 15. This is done so that the average player’s PER across the entire league is always 15 every season.
Detailed Formula:
The detailed formula for calculating PER involves specific coefficients for each type of statistic.
For example:
uPER=(1/Minutes Played)×(Credits−Penalties)
Where:
- Credits include all positive stats multiplied by their respective values (e.g., 1 point scored might contribute more than a single rebound).
- Penalties include deductions for missed shots, turnovers, etc.
After computing the uPER, you apply the pace and league adjustments:
aPER= uPER × Pace Factor
PER = aPER × (15 / League uPER)
Simplified Example Calculation:
While the specific weights and adjustments are proprietary and detailed by Hollinger, a simplified example might look like this:
- Calculate total credits from points, assists, rebounds, etc., using assigned values.
- Subtract penalties from missed shots and turnovers.
- Normalize this score per minute played.
- Adjust for pace to account for the game’s speed the player’s team plays at.
- Normalize to make the league-average PER equal to 15.
This process involves complex calculations and typically requires a spreadsheet or a statistical software package to calculate accurately for various players. The weights and factors change annually as they are adjusted based on the season’s data to maintain the league average at 15.
Overall, PER is designed to encapsulate a player’s statistical contributions into a single number, making it a useful but sometimes debated tool in player evaluation.
Example of PER in Use
Let’s consider a hypothetical NBA player, Johhny Bravo, and calculate a simple version of his PER over a game:
- Points: 28
- Field Goals Made: 10 (out of 20 attempts)
- Free Throws Made: 5 (out of 6 attempts)
- 3-Point Field Goals Made: 3
- Rebounds: 12
- Assists: 7
- Steals: 2
- Blocks: 1
- Turnovers: 3
Assuming the weights for points, field goals made, and other stats are predetermined by Hollinger’s formula, Johnny Bravo’s raw PER for this game would be calculated by inputting these stats into the formula, adjusting for pace, and comparing against league norms.
A simplified illustrative output might place Johnny Bravo’s PER for the game at around 25, indicating a performance well above the league average.
Historical Context of PER
John Hollinger developed PER in the early 2000s, looking to build a metric that could provide a complete picture of player performance.
Hollinger sought to capture all aspects of a player’s game into a single efficiency measure, reflecting his overall impact on the game during the time on the court.
PER was innovative because it was one of the first metrics to include a full range of basketball stats while adjusting for the game’s pace, setting the stage for the analytics movement in basketball.
Hollinger’s work on PER and other statistics eventually led him to roles within the NBA, influencing team decisions.
PER – Very Confusing, But Good To Know
PER remains a widely used metric for evaluating NBA players, offering a snapshot of their efficiency and productivity on the court.
While it has its critics, particularly regarding how it values certain types of players or contributions, PER’s ability to condense player performance into a single number provides a valuable tool for fans, analysts, and team executives alike.
As with all analytics, PER is best used in conjunction with other data to get the fullest picture of a player’s impact.
Check out some more advanced NBA metrics including True Shooting Percentage, Box Plus/Minus, and Usage Rate.
