Pressure
Pressure describes the defensive proximity a player faces when receiving or acting on the ball, computed from tracking data as the distance and number of opponents within a radius.
What it means
It is a property of the situation rather than of an event, so it must be sampled continuously rather than counted at discrete moments.
Why it matters
It is the ingredient that shot models and pass models most need and most often lack, and it is the main reason a tracking-data model outperforms a video-only model on the same match.
Where it is used
Tracking-derived shot and pass models, and the analysis of how much space a side creates for its players.
Where it misleads
It requires positional data, its radius and weighting are arbitrary, and it cannot distinguish a defender in front of the shooter from one behind him without further rules. Two providers can disagree about a shot purely on this ingredient.
Key points
- It needs tracking data and is absent from video-only feeds.
- The radius and weighting are choices, not constants.
- It affects shot and pass values materially.
- It cannot distinguish useful and useless proximity without more rules.
- Report the pressure model version when comparing tables.
- It is a property of situations, not a count of events.
A term is only as useful as the definition attached to it, and the definition has to travel with every figure quoted from it.