As baseball fans, we have been naturally conditioned to believe games are won and lost through hitting home runs, pitching shutouts and making great defensive plays. While this is mostly true, strained hamstrings and torn rotator cuffs also are crucial to determining which teams play in October and which teams mainly watch. Analysis over the past 50 years has revealed many truths in baseball, from the value of on-base percentage to the importance of a pitcher's strikeout rate to the relative value of defensive ability at various positions. But simply keeping players on the field is something we've had less success in analyzing.
Certainly, we can repair players much better than we used to. Modern surgical techniques might have given Don Drysdale and Ewell Blackwell fighting chances to continue their careers but probably would not have kept them off the shelf in the first place.
Going through transaction logs team by team (disabled list stats aren't generally kept and reported as neatly as stolen bases and walks), I've found 346 DL stints this season, totaling 11,323 days on the DL, or about 377 days per team. Team numbers range from less than 150 (White Sox, Rays) to more than 600 (Yankees, Rangers).
So, which teams have lost the most due to injury this year, rather than on-field play? Simply tallying DL days doesn't quite work, as not all injuries are built the same -- losing Josh Hamilton for a month is going to hurt a team a lot more than losing a utility infielder for a year.
To answer this question, I took the ZiPS-projected WARP for every player on the disabled list and prorated it for time missed. That alone won't tell the whole story, as these players weren't replaced in 2011 by a cloned army of theoretical replacement-level players, but real players who played well or poorly.
So, for each injury, I went game by game, to attempt to reasonably allocate playing time to a healthy squad. In some cases, this is fairly clear-cut, as in Kyle McClellan getting Adam Wainwright's expected starts, but in most cases, it's a bit messier. As such, I attempted to be conservative about allocating plate appearances and innings pitched, and spread the loss of backup playing time fairly evenly. Short of some marvelous technological advance mostly found in science fiction, we'll never be absolutely certain of what-ifs, but there's enough information to make educated guesses.
Let's take a look at the "healthy" standings, division by division:
Not a lot of change here, with New York's and Boston's injury losses being fairly typical for teams. While the Yankees have lost a lot of total injury time, players such as Colin Curtis and Reegie Corona were very unlikely to play major roles. And even with the losses of relievers Pedro Feliciano, Damaso Marte and Rafael Soriano, the bullpen has been very good. The Blue Jays have had some injuries, but most of the injuries to important players have been minor, enough that they likely would be edged out slightly by the Orioles with three months of Justin Duchscherer and Brian Matusz.