Doesn't sound like Turnbull will ever make a start again unless it's a de facto bullpen game in the last couple of weeks of the season. Seems to me the X factor here is the six-man rotation idea. That's two weak spots and stress on the bullpen in order to save the the other four pitchers. Which still might not be a bad idea, even if it means definitely not getting one of the top two seeds (but in that case you've just forced your first three pitchers to take an extra start and apparently your #4 has to go in the NLDS this year too).
Either way, this offense needs to have some crooked-number games to win with any of the #5s or a bullpen game.