Those who criticized the Vikings for drafting a safety in the second round because they didn't need one due to their signing of Madieu Williams, well, they look stupid now. (And yes, I think I was one of those, but I'm too tired too look that up, so I'll just assume responsibility). Thankfully, the Vikings' brain trust knew better, because otherwise the Purple would have to rely on Michael Boulware and, well, whoever they'd have been able to sign as the other backup safety. And that wouldn't cut it for the three games that Williams is likely going to miss.
The Vikings have now lost special teams ace Heath Farwell and backup defensive end Jayme Mitchell for the season and are unsure about whether Brian Robison will be able to play in the season opener. Mitchell's injury likely hurts the most, since it robs the Vikings of depth at defensive end, a position the Purple need depth at in order to be able to rotate linemen like they want to. And there have been a lot of players skipping practices to rest nagging injuries, including Bernard Berrian and, most importantly, Tyrell Johnson, who has had problems with his abdominal muscles.
There's really only thing that can derail this season (outside of Tarvaris Jackson playing like he did his rookie year) and that's injuries to the Vikings' crucial players. While injuries are a fact of life in the NFL, it sure seems like the Purple have had more than their fair share already, but thankfully, they've only lost one starter so far and only for three games. And yes, I know I just jinxed the Vikings. Still--there have been a lot of injuries.