I'm always scared when we draft a player, anyone can be a bust. The comparison to Sully is very idiotic. Sedrick Ellis and Glenn Dorsey are not even projected to be there when we pick and have one of the highest work ethics I have seen from a DT in a long time. Sully is the opposite. We reached big time drafting him and he did have work ethic issues, see where that got us.
Everyone is prone to injuries, some more than other though. Dorsey, even if he does have injury concerns, is not a talent to pass up. People had concerns with AP's health, and although he was injured, he took a team's offence, which had a horrible QB, to 10-6.
I know it's not the same comparing a DT to a RB. But defense revolves around a DT these days, and RB is a very intriquete part of an offence