Posted by Mike Lynch on March 15, 2018
As you browse Baseball Reference, you might notice some subtle changes to WAR figures on the site. There are four main reasons for this:
- Park factors for recent seasons have been re-computed to be three-year rolling averages. For instance, 2016 Park Factors now encompass 2015-2017. This is something that needs to be done when seasons end.
- We've incorporated restated and expanded fielding statistics from Sports Info Solutions. SIS's Defensive Runs Saved forms the basis for our Defensive WAR calculations since 2003. From 2011 on they recalibrated data using their timer measures to measure ball hang time. There was also some recalculation based on changing shift methodology. Though we're now publishing their catcher framing stat (Strike Zone Runs Saved), we have not incorporated it into WAR at this time.
- Pitchers who received time as position players (whether PH or in the field) are now being treated as part-time pitchers and part-time position players. Previously we treated them as full-time pitchers. Some pitchers like Red Ruffing, Bob Lemon and Jim Kaat appeared in many games as a position player, pinch hitter or pinch runner. We used to credit these PAs as pitchers, which overvalued their offensive contributions. To handle this, we compute a percentage of time as a non-pitcher and make an adjustment.
- Also, we have incorporated a good deal more Retrosheet data which has affected the years we can compute more advanced fielding and baserunning measures. We're now able to roll these measures back to 1953. Another important change is that with Retrosheet gamelogs back to 1908, we can now use their IP data back to that year to get starter/relief IP splits. Some pitcher WAR changes for 1908-12 are due to WAR now being calculated using gamelog IP rather than the "official" total listed on the player's stat line. The biggest difference here was the appropriately named Bugs Raymond. The "official" record credits him with 324.1 IP that season, but the gamelogs come out to 304.1, which significantly impacted his WAR calculation (see below). For further reading on discrepancies between "official" records and more recently produced gamelogs, please read this excellent explainer by Retrosheet's Dave Smith.
For further details on WAR and its calculation, please see this WAR explainer.
Here's a list of the biggest changes in WAR with this update:
Career pitching WAR: The biggest gain here is Lefty Grove, who went from 109.93 to 112.45. The biggest loser is Bugs Raymond, who changed from 7.26 to 5.91 due to his innings pitched change noted above. Of note, Clayton Kershaw's career pitching WAR saw an increase of 1.38 (ninth biggest bump), as it moved from 57.38 to 58.76.
Single-season pitching WAR: Bugs Raymond had his 1908 season adjusted from 5.16 to 3.66, again making him the biggest loser. The biggest increase was to Ed Karger's 1910 season, which went from 1.36 to 2.67. Of note, CC Sabathia's 2011 season is one of five pitcher seasons to change by 1.0 or more, but is the only one in the last 100 years. His changed from 7.47 to 6.42 due to the combination of his Park Factor changing from 108 to 105 and the defense behind him being given more credit. A recent pitcher season with a big jump is Corey Kluber's 2014, which went from 7.40 to 8.27, and makes him the 2014 MLB pitching WAR champ (passing Clayton Kershaw).
Career batting WAR: Red Lucas went from 14.08 to 11.65 thanks to changes in how we valued pitchers who were also pinch hitters. Yadier Molina was the biggest gainer here, as he moved from 35.35 to 37.07. A couple other active players made big moves, as well. Matt Wieters gained 1.66 WAR, while Jason Heyward lost 1.61 WAR, due to changes to the underlying fielding numbers.
Single-season batting WAR: Only one single-season batting WAR in the database changed by more than one win. That honor belongs to Ben Zobrist's 2011 season, which moved from 8.67 to 7.58, due to the changes to underlying fielding numbers. This means Zobrist is no longer the 2011 batting WAR champion. That honor now belongs to Jacoby Ellsbury, who moved from 8.10 to 8.31 WAR. The largest single-season increase in batting WAR belongs to Irv Noren. His 1953 season moved from 1.75 to 2.60. Yadier Molina's 2014 season saw the biggest jump among recent seasons, as it changed from 2.35 to 3.07. Another notable recent change is Carlos Gomez's 2013 season, which dropped from 8.49 to 7.83. This makes Andrew McCutchen (7.91) the new 2013 NL batting WAR champ.
To see full lists of the 1,000 largest changes to each of the above four categories, please click here.