You can move a pitcher to say, left field, from the mound, bring in a new pitcher, have him face a guy, then pull him and move the left fielder back to the mound, so I'm sure the current rules would let you swap them back and forth. At that point it's probably a question of is it bad on the arm to go hot, warm, hot, warm, that often? I don't really know the mechanics of it but I have to think there's a reason it isn't done...
Could we use the bullpen cart to ferry folks from the OF to the mound? That would speed the game up quite a bit.
