What are Offensive Shapley Win Credits (OSWC)?

Offensive Shapley Win Credits (OSWC) are a player’s fair share of credit for helping their team outscore the opponent in a game. The “Shapley” label is used because OSWC uses the Shapley Value from cooperative game theory for its calculation. The Shapley Value formula is a method for dividing credit among individuals involved in a collaborative team production that satisfies several mathematical fairness conditions.

The interpretation of OSWC is very simple: a player’s OSWC is the number of wins they deserve credit for creating. More precisely, it is the portion of the team’s wins for which that player deserves credit based on how their offensive contribution worked in collaboration with their teammates. Suppose a team wins a game and that OSWC divides credit for that 1 win such that player A is credited with 0.67 OSWC, player B is credited with 0.33 OSWC, and all other players are credited with 0 OSWC. Then the Shapley Value calculation determined that player A’s deserves credit for 0.67 of the 1 win while player B deserves credit for only 0.33 of the 1 win.

An important property of OSWC is that it fully allocates credit for wins so that the sum of OSWC for the players on a team exactly equals the total wins of that team. If the team wins 10 games, then the players’ OSWC add to 10. If the team wins 50 games, then the players’ OSWC add to 50.

Another property of OSWC is that it is a counting statistic that can be added across games, series, and seasons while retaining the same interpretation. If player A has more OSWC in a series than player B, then player A contributed more to outscoring the opponent in that series than player B.

The most distinctive property of OSWC is that it allocates credit based on how well the player worked with their teammates to outscore the opponent. That is, OSWC assigns credit based on the actual collaboration between teammates so that, for example, a double might result in more OSWC in one game than in another based on the different offensive contributions of the other teammates in those two games. This features makes OSWC fundamentally different from other statistics that attempt to remove the player from the collaborative context. For this reason, OSWC is a backward-looking statistic that reveals new insight into how to assign credit for what actually happened in a game, not a predictive statistic.