I'm not sure if he's a liability as much as the way their line works. They have two smaller primarily pass rushing DTs as starters. Their line was kind of weird and inverted, in that their DEs were great against the run and just OK pass rushers and their DTs were dominant pass rushers and just OK run defenders.
Stick Suh next to Brockers, and he will get it done even more than he currently does. Suh next to Fairley, however...That's some serious pressure, but in the run game they don't have enough strength IMO, so Suh is often stuck with double teams that he can't get through. With Brockers taking up blockers, (and Quinn and Long as well), Suh can play his style of football. Penetration and manhandling guys single handedly.
You're right about his attitude though.