Every now and then somebody gets bit by a shark, even though the odds are pretty much stacked against that happening...
Last season my team totally ran off the tracks before the all star game because most of my regular starting lineup suffered injuries, most of them more than a week. It was crazy bad luck, I'd never experienced that before. This season, I've gotten through so far without a single injury that last lasted more than one game after the injury happened. Injuries are just one of those things that happen.
I personally think that there should be some sort of hidden injury-risk factor (like Aggressiveness, which we all know exists and affects fouls though we can see the attribute) and that the injury risk should increase by age. But this has been discussed in past threads.
Don't ask what sort of Chunks they are, you probably don't want to know. Blowing Chunks since Season 4!