WAR
Wins Above Replacement (WAR) is a stat that combines measures of all aspects of a player's value to create one total figure that expresses the player's value in terms of wins provided to his team. There are multiple variations of WAR, but they all share the following criteria:
-contains measures of both offensive and defensive value for non-pitchers
-is expressed in terms of wins
-uses a replacement-level baseline that is at some point below average
-measures value provided by a player as opposed to the true talent or ability of the player
Replacement Level[edit]
WAR measures the number of wins a player contributes beyond the production a team can get from readily available talent by paying the league minimum. This readily available talent is the basis for replacement level. Examples of replacement level talent include players in AAA who are good enough to get some time in the Majors but aren't highly-rated prospects, waiver-wire pick-ups, nontenders, and minor league free agents. A replacement level player can be thought of as the 26th man on the roster.
Replacement level varies somewhat between different implementations of WAR. It is generally around two wins below average per full season.
The replacement level used for WARP at Baseball Prospectus was originally much lower than that of other WAR stats because both offensive and defensive value were measured relative to a replacement level well below average. In the company's 2009 annual, however, Clay Davenport announced that WARP would begin using a higher replacement level more in line with that used elsewhere.
Different Implementations[edit]
FanGraphs WAR (fWAR) FanGraphs WAR uses park-adjusted Tom Tango's position adjustments. fWAR currently has no consideration of catcher defense. Non-pitcher replacement level for fWAR is 20 runs per 600 PAs for both leagues.
For pitchers, fWAR is based on park-adjusted FIP. Replacement level is a .380 W% for starters and a .470 W% for relievers.
BaseballProjection WAR (rWAR, with an r for Rally) BaseballProjection WAR uses a Base Runs formula to create custom linear weights for each team which are then applied to that team's hitters to measure their offensive contributions. This ensures that the offensive runs of a team's players add up to the number of runs that team actually scored. rWAR also includes measures of value for baserunning (including non-SB baserunning), avoiding double plays, and reaching base on error. For defense, rWAR uses Total Zone and Sean Smith's position adjustments (similar to Tango's, but with catchers and first basemen a little closer to to average).
For pitchers, rWAR is based on runs allowed with an adjustment for team defense using Total Zone.
BaseballProjection uses a separate replacement level for each league to account for the difference in league quality.
