Posted by Sean Forman on May 17, 2010
This post is the seventh in our series of ten new features for our tenth anniversary.
Sabermetricians have always been on the search for the best way to measure wins contributed by players. Baseball Prospectus has WARP, Bill James has win shares and now we are presenting Sean Smith's Wins Above Replacement or WAR data on the site.
Here are some sample pages:
--Career WAR leaders
--Albert Pujols, Ryan Howard, and Dwight Gooden year-by-year WAR data (just below their batting stats).
--2009 NL Batting Leaders with WAR top ten
--1980 AL Team and Player Value Register
--WAR Pitching Leaders from 2000-2009 via the Play Index Season Finder
--The top shortstops of the 1990's by WAR via the Play Index Season Finder
--Most runs atttibutable to all baserunning events 1961-1981
--Most 6.0 WAR seasons by a pitcher in their career
--2001 Mariners Player Values (scroll past the fielding data)
We will be incorporating this data throughout the site, and your suggestions and comments are as always welcome.
Rough Sketch of How We Do This
A couple of items of note about our WAR data. First, the Runs values listed are all versus average. We have implemented WAR data for position players for the 2010 season, and will do so very soon for the pitchers.
--Rbat, batting runs are a linear weights formula utilizing custom weights depending on team runs scored and run scoring environment. For the current season this is adjusted batting runs.
--Rbsr, Baserunning events like stolen bases, advancing on passed balls, going first to third on a single. For 2010, this is currently just SB and CS data.
--Rroe gives a bonus or penalty depending on whether the player reached on error more often than average. Typically +/- 5 runs at the most. This is a relatively minor skill, but does in fact appear to be a skill. Not yet included for 2010.
--Rdp gives a bonus or penalty depending on whether the player grounds into more or fewer double plays than expected. Typically +/- 5 runs at the most. Not yet included for 2010.
--Rfield is the value in runs of all aspects of the player's fielding (fielding balls, outfield arms, turning the double play, controlling the running game).
--Rpos is the value in runs of playing a particular position. This is inversely proportional to the hitting ability of the average player at that position. 2009 values per 1,350 innings (150 games): Catcher 10 runs, Shortstop 7.5 runs, Second Base 3 runs, Third Base 2 runs, Center Field -2.5 runs, Right and Left Field -7.5 runs, First Base -10 runs, Designated Hitter -15 runs.
--Rrep is the value of an average player over a replacement player given the player's playing time. Replacement level is set at around a .320 team W-L percentage. AL's is 22 runs per 650 PA and NL's is 18 runs per 650 PA. A player's PA is the smaller of actual PA and 4PA/G*G in order to not overvalue leadoff hitters.
--RAR is the sum of all of the run components.
--WAR converts runs above replacement to wins above replacement. Runs per win is dependent on the run scoring environment the team played in. Currently using 10 runs/win for 2010 data. Will update this shortly.
--R pitcher's actual runs allowed
--Rrep runs allowed by a replacement level pitcher given this pitcher's defense, park, strength of opponents, and role (replacement level is different for starters and relievers). The number presented includes the defensive component, Rdef, already.
--Rdef runs above or below average for this pitcher's team defense. The team's overall defense weighted by the percent of balls in play allowed by this pitcher.
--aLI is the average leverage index this pitcher pitched in. To convert RAR to WAR, the pitcher's runs above replacement is weighted by the average of their leverage and 1.00 (due to bullpen chaining). Average leverage is 1.00. Above 1.00 includes high leverage and below 1.00 indicates lower leverage.
--RAR runs saved above replacement. This is not weighted by leverage yet.
--WAR RAR/(Runs per win), Runs per win varies with the run scoring environment of the pitcher and how that pitcher changes the environment. Typically around 10 runs per win.
A big thanks to Sean Smith for licensing this work to us and helping us get it updated during the season.