Playoffs sounds fair.

Regular season has to be done differently. I'd email both the owner and Mike regarding this. I'll assume you already did extended fielding to make sure someone wasn't also rated at C as a secondary position(such as Phillips or Wilson).

I'd suggest that repeated violations should incur a loss of a draft pick.

Thankfully anyone using only one catcher for the whole regular season will end up with a very tired catcher by the midway point of the season.