So in the playoffs, do we want to separate Muk and Joyce with a right handed hitter (Swanson?).
I think so. We know we are not pinch hitting for Muk. If they bat consecutively, we could have a situation where the other team brings in a lefty to face Muk, then we bring in Duvall to pinch hit for Joyce and the other team flips to a right handed pitcher. We burn a player without gaining the platoon advantage.
If/When the Cards bring in Miller to face Freeman through the bottom of the order, the Cards will not switch to a RHP if Snit PHs for anyone. They may pull Webb in response to someone PHing for Joyce and/or Mac. It will be important Snit doesn't fall into that trap and avoids burning PHers as you suggest is likely to happen.
The key to one of the games will probably be the Braves RHH PHers plus JD and Swanson doing something against Miller.