Pitch behind the back

[Dukat]

I have seen this girl in action in both High School (Her team took out my daughters team 2 years ago for the state championship) and college and she uses it as her changeup. It freezes the batters and is quite impressive looking. They did not allow it when she played High School but in college I have seen her use it 3 or 4 times a game in multiple games and is never called illegal. I think whenever she pitches they tell the umps beforehand so they will be ready for it.