As many have noticed, we have not been updating the 2012 WAR data in-season. The reason for this is that we have been working on a major upgrade to our WAR framework. The link above gives a very detailed rundown including: how to compute each part of our WAR formula, our reasoning on making the changes, downloads for historical WAR data, charts of the various constants and factors we use, and a chart of differences between the new B-R WAR, the old B-R WAR and FanGraphs WAR.
We also have pages describing the details of the components as well.
WAR for Position Players
WAR for Pitchers
How we compute wRAA for WAR
All in all, these are major improvements to the system and while there are dozens of details, here are the main points of difference between our old framework and the new one.
- Switch from BaseRuns for batting to an advanced wRAA metric.
- Folding ROE, infield singles, SO vs. Non-SO into wRAA.
- Excluding pitchers' hitting and averaging by league rather than year from the league averages for wOBA and wRAA.
- Estimation of CS numbers for leagues they are missing.
- Use of Baseball Info Solutions Defensive Runs Saved from 2003-present (in our view the most advanced defensive metric).
- Use of a player-influenced runs to win conversion for both batters and pitchers based on PythagenPat.
- Use of a player-specific park factor for pitchers weighted by actual appearances in each park.
- After a preliminary WAR calculation, we fine-tune the replacement level on a playing time basis, so the total WAR in each league is very consistent year-to-year.
- I've changed the oWAR and dWAR formulations. oWAR is now called ndWAR for (no-defense WAR), but is the same otherwise. dWAR now contains the position component of WAR, so the Career Leaderboard is now dominated by SS, C and other great defensive players.
As always our goal is accuracy and we think this gives us a more accurate system. As suggestions, tweaks, and more data comes in we'll continue to adjust the system.
One other thing we are doing is providing a daily updated download of our WAR totals for every major league player. Batters and Pitchers. Feel free to use it how you wish so long as you cite us. If you prefer the old numbers they are available for download from About index.
I owe a big thanks to many people, but wanted to single out the following.
Sean Smith, who provided us with the original WAR incarnation on the site and provided much of the methodology used including, but not limited to TZR (pre-2003), GIDP runs, Baserunning Runs, Replacement Level, and Pitcher WAR.
Baseball Info Solutions licenses up their tremendous defensive metrics.
Tom Tango, who provided us with a great deal of feedback related to modifying and improving on wRAA and runs-to-wins calculations.
Neil Paine, who walked through each step of this rethinking with me.
RetroSheet and Pete Palmer for the raw batting, pitching, and fielding numbers that go into the system.
This entry was posted on Friday, May 4th, 2012 at 11:11 am and is filed under Announcement, Baseball-Reference.com. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.