As far as I know, injuries are random. The only thing that increases injury risk is playing against a team that commits a lot fouls, since that is the only way that injuries occur. If you want to debate this last point, I am positive that there have been threads in the past that get into that issue (since I've posted in those threads before).
Don't ask what sort of Chunks they are, you probably don't want to know. Blowing Chunks since Season 4!