The answer is Tony Allen is a useful player on a terrible team when he can get minutes, but his lack of discipline, turnovers, and low basketball IQ limit his presence on a good roster.
If the choice is between playing Tony Allen OR Paul Pierce, Ray Allen, or James Posey ... there really isn't a choice. Tony Allen is a liability compared to those guys.
He will move onto to a bad team, get minutes, and be the same frustratingly talented player he was with us. Good enough to show flashes, but over a prolonged period of time; he is the type of player that will get a coach fired.