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".[1] 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.[2]
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.[2] 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.[2] A high WAR value built up by a player reflects successful performance, a large quantity of playing time, or both.