I had a 9yr old once whose back was getting a slight tilt. Parents told the DR she was a pitcher so the Dr told them to also put her other sports to equal out her activity on both sides. So they put her in tennis. I guess she didn't like swimming.
JoJo, your example is really interesting. When my DD was 10U she played with a young lady that was a standout as a pitcher and tennis player. She hurt her shoulder and hasn't played softball since.