If you had to pick one NFL team that has been most affected by injuries so far this season, the Indianapolis Colts, who face the Tampa Bay Buccaneers on this week's "Monday Night Football," probably would be it. For Indianapolis, Peyton Manning's absence has not surprisingly rendered its offense highly ineffective. This week, any hope that the defense could keep the team afloat until Manning returns -- if he returns at all -- took a hit when the Colts placed starting middle linebacker Gary Brackett and starting strong safety Melvin Bullitt on injured reserve.
Defensive injuries are nothing new to Indianapolis, as Colts fans can attest. It turns out this is one case where numbers match perception. From 2006 to 2010, Indianapolis lost more starter games because of injury than any other defense in the NFL, and it's not even close.
Of course, missing games is not the only way injuries affect teams. When a player takes the field after having been listed as questionable on the Friday injury report, he's not playing at 100 percent, and that negatively impacts performance as well. At Football Outsiders, our adjusted games lost measure takes this into account. Even in the case of AGL, Indianapolis has had the most injured defense in the league in the past five seasons.
Also interesting about the injury woes of units like the Colts' defense, however, is that not only has it suffered a ton of injuries, it consistently suffers a ton of injuries season after season: Beginning in 2006, Indianapolis ranked 28th, 32nd, 25th, 30th and 31st in defensive AGL. The Cleveland Browns' and Cincinnati Bengals' defenses have been in the same boat, also having ranked 20th or lower in each of the past five seasons.
This begs the obvious question, "Why?" In our win projections before the season, we assume that injuries are random, such that teams who suffer an extreme number of injuries one season are likely to be closer to average the following season (i.e., regress toward the mean). However, what are we to make of teams like Indianapolis, Cleveland and Cincinnati, which appear to have some structural defect that makes them prone to injury every season?