Actually, my DD has a cast one her right (throwing) arm due to a broken finger. We bubble-wrapped the cast and put a sock over it, and she was our catcher's courtesy runner for the first 2 games this morning.
A friend of our's DD is a pitcher. She broke her hand last season. When dad took her to the doc, the doc asked if she had her glove, so he could fit her cast perfectly so she could still play. And she did.