Wins Above Replacement

Wins Above Replacement or Wins Above Replacement Player, commonly abbreviated to WAR or WARP, is a non-standardized sabermetric baseball statistic developed to sum up "a player's total contributions to his team". A player's WAR value is claimed to be the number of additional wins his team has achieved above the number of expected team wins if that player were substituted with a replacement-level player: a player who may be added to the team for minimal cost and effort.

Individual WAR values are calculated from the number and success rate of on-field actions by a player (in batting, baserunning, fielding, and pitching), with higher values reflecting larger contributions to a team's success. WAR value also depends on what position a player plays, with more value going to key defensive positions like catcher and shortstop than positions with less defensive importance such as first base. A high WAR value built up by a player reflects successful performance, a large quantity of playing time, or both.

For example, FanGraphs rates Clayton Kershaw's 2014 regular season performance at 7.9 WAR, suggesting his team won roughly eight more games than would be expected if his innings had been pitched by a replacement level player. Kershaw achieved this high WAR total by pitching many innings while maintaining a high rate of strikeouts and low rates of home runs and walks.