Effectiveness (EFF) attempts to determine how effective a player is on the ice. EFF considers Time-On-Ice, Points (in the case of OEFF), and +/-.
Offensive Effectiveness
OEFF is determined by adding the player's points with their +/- and dividing the sum by the seconds-on-ice. I multiply this number by 1000 for readability.
OEFF = ((points + plus-minus) / seconds on ice) * 1000
Defensive Effectiveness
DEFF is even simpler to calculate as we remove the benefit of offense from the OEFF. The sum is also multiplied by 1000 for readability.
DEFF = (plus-minus / seconds on ice) * 1000
Overall Effectiveness
To determine a player's overall effectiveness, we add OEFF and DEFF.
EFF = OEFF + DEFF
Rationale
The focus of EFF is not productivity but effectiveness. The questions being answered are:
- How effective is this player when deployed on the ice?
- How likely is it that the player's team team will score when this player is on the ice?
- How unlikely is it that the opposing team will score when this player is on the ice?
The higher the EFF, the more effective they are. Players with an EFF under 0 can be considered ineffective.
Calculating the time-on-ice into EFF adds much-needed context to the raw +/- metric. For example, here are two players from the 2022-2023 season.
| Name | OEFF | DEFF | EFF | Points | +/- | Time on Ice | Seconds on Ice |
|---|---|---|---|---|---|---|---|
| Filip Chytil | 0.92 | 0.23 | 1.15 | 45 | 15 | 1086:36 | 65196 |
| Chris Kreider | 0.859 | 0.241 | 1.1 | 54 | 21 | 1454:38 | 87278 |
Because of the 368 minutes (~6 complete games) of ice-time disparity, Chytil and Kreider were nearly equally effective despite the relatively wide gap in points and +/-.