April 16, 2013

BP Announcements

Historical Pitcher DL Data at Baseball Prospectus

by Corey Dawkins

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After more than five years and countless hours of research, it is my pleasure to announce that disabled list transactions at Baseball Prospectus are now complete for pitchers going back to the late 1940s, and available on the “Injury History” section of the player cards. There are several points to be aware of before you dive in:

1. I have no access to team records and therefore need to rely on public sources. To complete this project, I drew upon several sources in order to find the most accurate information possible, including Retrosheet, MLB.com, ESPN, Associated Press stories, The Baseball Encyclopedia, NY Times archives, Boston Globe Archives, and numerous others. Unfortunately, no single source was entirely accurate. Information was crosschecked between them and reviewed to find the most accurate medical information possible.
2. If a starting pitcher is injured but either misses no time or recovers in time to make his next start, the “Date On” and “Date Off” listed will be the date of injury. For instance, if Ryan Dempster had left yesterday's game with a foot contusion but had gone on to make his next start, the “Date On” and “Date Off” displayed would have been 4/15/2013. If he’d injured his foot and gone on to miss time, though, the “Date On” displayed would have been the day following the injury.  
3. The convention is the same for relief pitchers. If a reliever suffers an injury but returns to pitch the next day, his “Date On” and “Date Off” will be the day of the injury.
4. Other sites and references often use the day of placement onto the DL as the “Date On” instead of citing the day after injury as I do.
5. Before 1991, the number of players that could be placed on each team’s DL at one time was limited. Therefore, many injuries (especially pre-1980) that would otherwise have called for a quick DL stint (hamstring strains, ankle sprains, etc.) went without one because of more serious injuries to teammates that occurred at the same time. Collecting information on these other injuries is another project in the works, but it will be a while before that will be complete.

In the coming months, I will be working on getting the disabled list transactions for hitters entered into the database and uploaded to the player cards. In the interim, please enjoy the research that will surely come down the pipeline and let me know if there are any questions or concerns.

Corey Dawkins is an author of Baseball Prospectus. Follow @CoreyDawkinsBP
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