Before we even get started, a big tip of the cap to Bilfer, who used to run the Detroit Tigers Weblog. He went over these rules in 2009 and we've probably all cited them since. Also he provided a link to Keith Law's (now outdated) review of the rules from 2007. I also read the Baseball Prospectus article from last year. Thanks to reader Nick for this link, and to Matthew B Mowery for some help on Twitter.
Note: After learning a bit more information, updates appear throughout this post.
Although we Tigers fans know thinking about the playoffs in August sometimes ends in disappointment a month later, baseball general managers have to think about the playoff roster weeks ahead of time. (Actually, savvy GMs should be thinking about moves that expand the playoff eligibility roster all year 'round.) But playoff eligibility rules can be a bit confusing, so hopefully this post will clear some things up. Hopefully.
Billfer began his story in 2009 so succinctly I'm just going to quote from it:
To be eligible for a team’s playoff roster a player must be on either a) the 25 man active roster, b) the disabled list, c) the bereavement list, d) the suspended list as of August 31st at midnight.
Sounds simple enough, right? Well, it gets a lot more complicated when you begin to consider the substitutions that can be made for an injured player come playoff time. So practically speaking, you're not setting your playoff roster on Aug. 31 quite as much as you're setting the pool you'll be able to select from. However, you're not limited to this pool. You can replace an injured player with another player.
from a similar position (pitcher for pitcher, position player for position player).
For instance, right now Detroit has 12 pitchers and 13 position players on the active roster. All those players are eligible for the playoffs. In addition, Al Alburquerque, Carlos Guillen, Joel Zumaya and Brad Thomas are eligible due to being on the DL. So by not activating Alburquerque and Guillen before Sept. 1, Detroit gets another two players on the eligibility list.
Update: Because Zumaya and Thomas will still be injured when the playoffs begin, they can be replaced by any player who is in the organization as of 11:59 tomorrow night, regardless of position.
In 2007 Red Sox director of baseball operations Brian O'Halloran was quoted by the Boston Globe:
"The position-player-for-position-player / pitcher-for-pitcher requirement is indeed now gone for substitutions prior to a series," O'Halloran wrote in an e-mail. "However, teams now are allowed to substitute for an injured player during a series. Such in-series substitutions are position-player-for-position-player / pitcher-for-pitcher, and the injured player cannot be active for the remainder of that series or the next series. Those substitutions also require MLB approval.
So practically speaking, we're looking at this player pool:
Eligible (as of right now) position players (14)
Eligible (as of right now) pitchers (15)
Al Alburquerque (15-day DL)
Brad Thomas (60-day DL)
Joel Zumaya (60-day DL)
As I mentioned above, any player can be substituted for Thomas and Zumaya. So there are two bonus players that do not have to be on the active roster when the calendar changes to September.
As far as I can tell from what I've read, there isn't a ratio of position players and pitchers to worry about, you just have to draw your selection from the eligible players. So I don't think you have to worry about the 13 and 12 things so much as you have to worry about making sure any players you might want to use are eligible. However, experts please correct me if I'm wrong.
By the way, teams have to set their divisional series roster a day before the playoffs begin, but they can change the roster between playoff rounds. They can also replace a player who is injured during the playoffs. However the injured player would not be eligible in that or in the following round.
Questions? Comments? (Gulp, corrections?)