He's been a starting quarterback in this league for eight years and only once has he played every game of a season. What makes Vick different than an injury-prone player like Bob Sanders or Darren McFadden is that a quarterback isn't supposed to get hit as often as other players on the field.
However, because of Vick's love to run the ball without sliding and his overall appeared frailness, Vick has missed a total of 29 games in eight years. He even injured his hand during his first preseason game, and while the injury isn't serious, it still shows just how easy it is for Vick to get banged up.
If there is one thing that remains constant year after year in the NFL, it's that Vick is going to miss some time during the season because of an injury. Now if that isn't being injury prone, then I don't know what is.