Someone up there has a seriously twisted sense of humor. That’s really the only explanation for the three horrifically timed injuries in the NFL this weekend. First, in his first practice after Brett Favre’s continued retirement made him the likely Vikings’ starter, QB Tarvaris Jackson sprained his MCL . It doesn’t seem to be particularly serious at this point, but knee injuries can definitely linger for quarterbacks. He could miss just a couple of days, or he could be out for a couple of weeks or more. Either way, this will be a good chance for Sage Rosenfels to seize the advantage in the QB race if he is up to it.

Karma struck again on Saturday – hours after signing a five year deal with the Cardinals, Beanie Wells was carried off the field on a cart with an ankle injury. It’s still not clear how long he will be out, though it doesn’t appear to be truly serious. Again, though, this will put Wells in a disadvantage in his attempt to beat out Tim Hightower for the starting running back job. The irony here is that one of the reasons it took this long for a deal to get done is probably because the Cards were a bit concerned about the injury issues that plagued Wells last year.

Finally, Broncos wide receiver Brandon Marshall was forced to sit out of practices after tweaking his hamstring. Marshall is reportedly more than a little disgruntled with the Broncos and new head coach Josh McDaniels , and has been trying to get sent to another team. It’s not likely to happen at this time of year, but especially not now – a receiver who can’t run isn’t particularly attractive. Marshall and new QB Kyle Orton will need to quickly develop chemistry for the sake of the team and the new QB, so missed time here could be costly.