Fantasy Football Analytics Lab

Why box scores mislead

A box score records what happened, not how likely it was to happen again. A receiver with two touchdowns on three catches had a great week and told you very little about next week. Advanced metrics exist to separate the part of a performance that reflects a role from the part that reflects a good afternoon.

The practical use is timing. Efficiency and opportunity metrics move before fantasy points do, so they identify players about to be good while they are still cheap, and players about to disappoint while they are still expensive. By the time the points confirm it, the trade window has closed.

What these metrics measure

• Efficiency per play: value generated each time a player is involved, which does not flatter whoever simply plays the most.
• Opportunity share: how much of an offence runs through a player. The most stable predictor there is, and the first thing to check.
• Air yards and target quality: not all targets are equal. Ten downfield looks and ten screens produce very different ranges of outcomes.
• Expected versus actual: the gap between what a player's usage should produce and what it did. Large gaps close, in both directions.