I don't know if this been considered: What about send Dunn to AAA for awhile and get intense coaching and a chance to (hopefully) destroy AAA pitching. Figure out what needs to be figured out for awhile, and if he has success with that assignment, come back to the big leagues.
Maybe Dunn has to OK this, but how could he not have the integrity, at this point, to do whats right for the team as well as any hope of productive
MLB career. What else is there to do besides ride the bench?