Wednesday, August 20, 2025

More Thoughts on Basketball Efficiency

What does 'efficiency' mean for a basketball player? There's the 'eyeball' reading and analytical metrics.

It makes sense that more positive contributions and fewer negative ones result in higher efficiency. I wrote about this first in 2015, although it was not a new concept. 

NBA and WNBA player efficiency calculations differ. ChatGPT explains:

The WNBA Player Efficiency Rating (PER) is a measure of a player's per-minute productivity, similar to the NBA's version created by John Hollinger. The WNBA does not officially publish PER on its website, but basketball analysts and advanced stat sites calculate it using the same core formula.

Here’s how PER is generally calculated (same as in the NBA, with WNBA-specific stats plugged in):

Formula (Simplified Overview)

The basic structure of PER is:

PER=1/Minutes×(Positive Contributions - Negative Contributions)×League Adjustment)

But in practice, it’s a very complex formula that includes:

Positive Contributions:

  • Points

  • Assists

  • Rebounds (Offensive and Defensive)

  • Steals

  • Blocks

  • Free Throws Made

  • Field Goals Made

  • Three-Pointers Made

Negative Contributions:

  • Turnovers

  • Missed Field Goals

  • Missed Free Throws

  • Personal Fouls

Complete Calculation (Highly Technical)

Hollinger’s original formula weights each action using statistical constants and adjusts for:

  • Team pace

  • League averages

  • Minutes played

The detailed equation includes terms like:

uPER=1MP[(3P)+23(AST)+(2−FGM)+0.5(FTM)−VOP⋅TO−VOP⋅DRBP⋅(FGA−FGM)−VOP⋅0.44⋅(FTA−FTM)+VOP⋅(1−DRBP)⋅(TRB−OREB)+VOP⋅DRBP⋅OREB+VOP⋅STL+VOP⋅DRBP⋅BLK−PF⋅(lgFT/lgPF)]uPER = \frac{1}{MP} \left[ (3P) + \frac{2}{3} (AST) + (2-FGM) + 0.5 (FTM) - VOP \cdot TO - VOP \cdot DRBP \cdot (FGA - FGM) - VOP \cdot 0.44 \cdot (FTA - FTM) + VOP \cdot (1 - DRBP) \cdot (TRB - OREB) + VOP \cdot DRBP \cdot OREB + VOP \cdot STL + VOP \cdot DRBP \cdot BLK - PF \cdot (lgFT / lgPF) \right]

Where:

  • VOP = Value of Possession

  • DRBP = Defensive Rebound %

  • lgFT = League FT made

  • lgPF = League Personal Fouls

Then the league average is normalized to PER = 15.0.

Alternative: Efficiency (EFF)

The WNBA does publish a simpler version called Efficiency (EFF), often used by broadcasters and box scores:

EFF=(PTS+REB+AST+STL+BLK)−(FGA−FGM+FTA−FTM+TO)

This is not PER, but a rougher and easier-to-calculate metric of total productivity.

Summary

MetricUseProsCons
PERAdvanced stat sitesAdjusted for pace, team, and leagueComplex and less transparent
EFFBroadcast & WNBA.comEasy to calculateDoesn’t adjust for pace or context

If you're tracking player impact in the WNBA and need a balance of accuracy and clarity, EFF works for casual analysis, while PER is better for deeper insights when calculated correctly.

If you wanted to apply one to high school or youth play, the latter is much easier.

How can we "be a scientist" not a preacher as a coach? 

"Possession enders" get scores and help get stops (steals, blocks, deflections, defensive rebounds). 

Inefficiencies show up as turnovers and high volume shooting without many points. Neither Hollinger PER or WNBA "Efficiency" show up as defensive rating. 

Here's a link to the most current WNBA stats ranked by Player Efficiency. Napheesa Collier had been the league leader but A'ja Wilson has slipped ahead. Note that Angel Reese is a highly productive fifth.  

Here's a link to current WNBA defensive player ratings, sorted by those playing at least 20 minutes/game. Individual defensive ratings will depend to some extent on team defensive rating. For example, Dallas trails Indiana by 6.3 points per game so comparing individual defensive ratings might take that into account. 

Analytics don't replace the 'eyeball test'. They add to it. 

Lagniappe. Maintaining relationships with coaches and players is a blessing. 

Lagniappe 2. Effort, unselfishness, body language, character...and you have to be a player... 

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