My 13 year old dd grew 6 inches in about 8 months. She couldn't even pitch the ball to home plate after being able to pitch 54-56. This lasted about a year. she could "K" the ball about 50mph, but get the rest of her body involved and it wouldn't be anywhere near the plate. Very frustrating for her. Almost gave up pitching totally. She is now 15, 6'2" and is hitting 60+. Everyone may have different result when going through a growth spurt but I do feel sorry for the girls that it affects negatively. We always hear just wait til she grows into her body but everyone expects a tall pitcher to throw hard now!