I think Bradley would be very effective in that role, though I'd personally rather start him with butler as i feel their skills compliment each other better.
Crowder could certainly be a good bench player, but having him in that role i would feel like i am holding back his career. Id feel he could go elsewhere and have a real impact role as a starter.
Butler and Bradley? I hope Butler suddenly turn into a point guard, because that's not gonna work.
Bradley off the bench is a fine idea, he'll cause havoc against second line offensive players with his D, and he successfully attacks early with his jump shot in most cases. On paper it seems like a fit. And I don't think he'll really mind too much.
Depending just who is on the floor with Crowder is important when considering him a starter. His aggressive defensive play, and never back down attitude say starter, his limited scoring says other wise.