The NFL's injury epidemic began even before any preseason games were played, with Sean Lee and Kiko Alonso going down.
Since then, big-name players (RG3, Robert Mathis, Knowshon Moreno, Sam Bradford, B.J. Raji, DeAngelo Hall, Chris Long, Ike Taylor) have been sidelined, and entire units such as Atlanta and Philadelphia's offensive lines and Carolina's backfield have been ravaged.
What gives? ACLs, Achilles tendons and shoulders, among other things.
Consider what has happened to the Vikings, who lost quarterback Matt Cassel (broken foot), and right guard Brandon Fusco (torn pectoral muscle) for the season. Tight end Kyle Rudolph (sports hernia surgery) will miss about six weeks.
That almost makes linebacker Chad Greenway's hand and rib problems from which he will soon return seem tame. Almost.
''I never envisioned that, but it's a part of football,'' Vikings coach Mike Zimmer said after all of those injuries occurred in one game. ''Last year in Cincinnati we lost our best defensive tackle, our best corner, one of our best linebackers, a very good defensive end. Things happen in the NFL, so this is a survival of the fittest game, it's always a marathon.''
Marathon or sprint, it's difficult - sometimes impossible - to stay on track with so many players getting hurt. Although injured reserve numbers are not significantly different at this point from recent seasons (39 in-season through four weeks last year, 41 this year), they remain alarming.
Going back to the summer, a total of 262 players have gone on injured reserve, with only 21 of them designated to return this season.
Many of those players who went on IR before the season might not have made teams anyway.
Judging only by IR numbers, according to STATS, linebacker far and away is the most vulnerable spot to injuries with 54 already in 2014.
That includes such critical members of their defenses as Lee in Dallas, Alonso in Buffalo, Sean Weatherspoon in Atlanta, Derrick Johnson in Kansas City, Jarvis Jones in Pittsburgh, Nick Roach in Oakland, Danny Trevathan in Denver, and Zach Brown in Tennessee. Not all of them are on IR, but their lengthy absences are damaging.
Detroit saw LB Stephen Tulloch suffer the weirdest of all injuries, tearing his ACL while doing a mocking celebration after a sack of Aaron Rodgers.
More troubling is when the likes of Hall and Johnson are sidelined with Achilles tendon tears even though they are not involved in contact when they get hurt.
''There are like 14 of these in the National Football League right now,'' Chiefs coach Andy Reid said of Achilles injuries. ''Three teams are in double digits with them (players on IR). So it's out there and people are examining it to try to figure it out.''
Running back and wide receiver have the next highest numbers on IR, 34 and 33.
Injuries are unavoidable in such a violent sport, and football on all levels has been criticized for how head trauma and concussions were handled for years. The NFL has instituted some rules, particularly those protecting defenseless players, that it hopes will cut down on injuries.
Still, with the players bigger, faster and in better shape than ever, and with equipment that, at times, can become weapons, football never will be injury free. Or anything close.
So teams try to adapt. But when they get racked at the same positions or units, it often is a critical blow to their chances for success.
Under the salary cap, and with the large gap between starters and backups - particularly outstanding starters and inexperienced backups - injuries often are decisive.
Carolina won the NFC South last season and got off to a 2-0 start in 2014. But with their backfield a wreck, the Panthers were drubbed the past two weeks as Pittsburgh and Baltimore could concentrate on stymieing QB Cam Newton.
''The injuries that have plagued our running backs is almost hard to believe,'' says tight end Greg Olsen, referring to losing for the short term DeAngelo Williams (ankle), Jonathan Stewart (knee), and Fozzy Whittaker (hamstring), and for more than half the schedule, Mike Tolbert (hairline leg fracture, on IR/designated to return).
''You talk about having four active running backs on Day 1 of the season and every single one of them gets injured. I mean, what are you going to do? It's a crazy thing. You can go years without having a running back get hurt and we have our top four guys out.
''But that's the NFL. There are a lot of teams banged up and we have to find a way to get through.''
Yes, that's the mentality. The season is a battle of attrition, and it might not always be the most talented teams that prosper, but the healthiest.
With health being relative, measured perhaps by having the fewest major injuries.
''I think you want to be at full strength,'' Broncos coach John Fox says. ''Unfortunately in this league not everybody is, and so I mention it every year: You need some good breaks and injuries are part of those good breaks - being healthy. Like I mentioned a year ago, we had seven guys on IR that were starters and we made it to the Super Bowl.
''So you just knock on wood and try to remain healthy.''
AP Pro Football Writers Dave Campbell and Arnie Stapleton and Sports Writers Steve Reed and Dave Skretta contributed to this story.
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