Injured reserve tells only a partial story, of course, because it doesn't account for those who are healthy enough to remain on the active roster while they rehabilitate. A more encompassing analysis is missed starts, which are up about 14 percent this season based on a database maintained by ESPN.com senior writer John Clayton. New concussion protocols almost certainly have contributed to that escalation.
The NFL's competition committee analyzes similar numbers every offseason, from season-ending injuries to missed starts to missed practices. Polian spent two decades as part of that group and cautioned against cementing a theory before the end of a season.
When he was with the Indianapolis Colts, in fact, Polian conducted an injury study of seven seasons under coach Tony Dungy. Among other things, the analysis revealed that injury totals typically spiked in Week 9 and slowed down thereafter.
"And that reflected what we saw in subsequent years and also what the competition committee saw for the league," Polian said. "To say anything definitive right now is purely conjecture."
There is no denying, however, that certain segments of the injury story are alarming. For instance, more players have already been placed on injured reserve because of confirmed ACL tears (38) than in all of 2012 (32) or 2011 (25), according to ESPN Stats & Information.
Meanwhile, nine quarterbacks went on injured reserve in the first 10 weeks of the season, the second-highest total in 15 years at that point in the season. (Ten quarterbacks went on injured reserve before Week 11 of the 2008 season, including Tom Brady and Alex Smith.) Forty-eight players have made at least one start at quarterback through 12 weeks. (A total of 47 quarterbacks got at least one start in all of in 2012.) Seven teams have started two quarterbacks this season, and five more have started three. Meanwhile, there are countless bits of anecdotal evidence to fortify concerns:
• For a Week 10 game against the Redskins, the Minnesota Vikings had more players unavailable due to injury than they had spots on their seven-man list of inactive players. So they dressed only 44, two short of the limit, and that included No. 3 quarterback Josh Freeman. Coach Leslie Frazier felt compelled to take timeouts at the end of the game to rest his defense, even though it aided the Redskins' comeback attempt.
• The New England Patriots are playing with a significant hole in their defense, having lost nose tackle Vince Wilfork and linebacker Jerod Mayo over a three-week period. Sunday night, the Patriots allowed 280 rushing yards to the Denver Broncos.
The NFL has worked hard to legislate some injuries out of the game, most notably via new rules to protect quarterbacks in the pocket. But Dr. Mark Adickes, a former NFL player who is now an orthopedic surgeon in Houston, suggested a level of physiological inevitability.
"Quite simply, guys are getting bigger, stronger and faster," Adickes said. "If you're getting bigger, stronger and faster, then as you run or even just move around, if muscles aren't firing just right, you'll see forces that can't be withstood without an injury."