I disagree with Broc. I in fact do believe in the Madden curse, to an extent. I'm one of the biggest superstitious guys around. I mean before Superbowl 2010, I didn't tie my shoes for 2 months. Although we lost...so that was kind of point less. After that I stopped doing things like that, but I still believe in those types of things.
I mean I think it has more to do with the success they're having. If they're on the cover, obviously they're doing good. Injuries happen all the time, especially when right then you're at the top of your career. I'm not saying it's all coincidence...and it's pretty easy to keep the curse going, when part of it is "OR your team has a bad season" which pretty much means not winning the Superbowl or having a non attention grabbing statistical game.
Injuries happen all the time though, to big players too. Especially when they're on top of the word and have everything going their way. Adrian Peterson could have won the cover instead of Peyton Overrated. He still would have had that horrible ACL injury, and it would have all been blamed on the cover. Same goes with Mendenhall, or Peyton Manning, or anyone else who got hurt this year or had a bad season. What if Danny Woodhead got on the cover? Let me guess, losing the Superbowl falls under the curse too?
I don't know though, it seems that something does sort of happen though every year, so it's kind of nice to play along with it.