Setting aside the question of the PE class (which I would take up with the AD and/or the Principal if need be), you have all the leverage because you have the pitcher. Without a pitcher, the coach has no team and will lose every game. If they are not prepared to amend their currently insane plan to ensure they have a quality pitcher for the Varsity season, then they are just a moron.
Developing the JV pitcher is part of the answer as is trying to identify any former pitchers or athletic girls on the roster and getting them to a place where they can at least somewhat reliably throw strikes to eat innings.
Developing the JV pitcher is part of the answer as is trying to identify any former pitchers or athletic girls on the roster and getting them to a place where they can at least somewhat reliably throw strikes to eat innings.