XVAL represents the amount of excess value produced by a player. It is not simply the value the player has produced, but it is the value they have produced above & beyond (or in some cases below) what they have been paid. It is derived from calculating the total value produced by a player (WAR * Win Value) then subtracting the amount of salary the player has been paid through that given point in the season. For a more detailed definition visit our blog post: What is XVAL?

WAR (Wins Above Replacement) is a baseball statistic that represents how many more wins a player would give a team as opposed to a "replacement level", or minor league/bench player at that position.