Win probability added (WPA)

Win Probability Added (WPA) is a statistic used in baseball to measure how much a player influences the chances of their team winning a game. It tracks the change in the team's likelihood of winning before and after a player's action—such as a hit or a strikeout. If a player's play increases the team's chances of winning, they have a positive WPA; if it decreases the chances, their WPA is negative. Summing these changes over a game provides insight into a player's overall impact on their team's success in specific moments.