He could still get two more starts on full rest if he pitched Tuesday. He definitely wouldn't be available for Game 1 of the playoffs, but I'm more worried about the division right now.
Now's not the time to mess with the rotation again. Pitch Z on 3 days rest and then the next time he pitches is on 5 days rest? I don't know how much "routine" goes into his pitching, but I wouldn't mess with it any more than they have.