They need to do what is best for the team. Nothing more or less. But he's not earned the right to make that decision. It's not a players job to do so, and the vast majority would never take themselves out or move to a new position on their own. The FO and manager need to run the team, and the players play.
As for DH or not? I mean, they have four starters, rotate thru DH. But if he's healthy next year, I'd trust him to field more than Keaschell....