Evaluating a player's passing decisions by comparing the pass they chose to all the passes they could have chosen. For every passing moment, compute risk and gain for the actual pass AND for hypothetical passes to every other reachable teammate. Then measure: (1) Risk Decision Parameter — what percentage of the time does the player choose the lowest-risk option? (2) Gain Decision Parameter — what percentage of the time does the player choose the highest-gain option? These two parameters capture the player's decision-making style independently of their execution quality. The key insight: "when you are valuing actions of a player you should take into account the options the player had."
(1) For each passing moment, identify all reachable teammates from 360 data. (2) Compute risk and gain for a hypothetical pass to each teammate (using the kinematic simulation from pass-risk-gain-decomposition). (3) Rank the options by risk (lowest risk = safest) and by gain (highest gain = most attacking). (4) Check: did the player choose the lowest-risk option? → increment risk decision counter. Did they choose the highest-gain option? → increment gain decision counter. (5) Average across all passes for the player: Risk Decision Parameter = % of times chose lowest risk. Gain Decision Parameter = % of times chose highest gain.
Key findings from Barcelona (37 matches, 2020-21):
Across a full season of Barcelona data, risk decision parameter decreases and gain decision parameter increases in the second half. Players systematically take more chances as the game progresses — even controlling for score line. This temporal shift is measurable and exploitable.
EPV of a chosen action minus EPV of the best alternative gives the "added value" of the decision. If a player's best alternative was a 0.10 EPV pass and they chose a 0.12 EPV pass, their added value is 0.02 — not 0.12. A player who consistently finds the 0.02 improvement over the obvious option is elite. A player whose choices match the best obvious option has adequate but not exceptional decision-making. A player who consistently chooses below the best alternative is costing the team.