Attached is a progression of the pitcher I mentioned. In the middle frame, her back foot of roughly two inches off the ground. It's less clear from a picture than in real life. Terrifically effective pitcher. She looks a lot like Angel Bunner. She is clearly getting an extra push from her back foot replanting. These are stills from a video I took. She leaps at least two feet beyond the pitcher's plate before she releases.
She does this every pitch and I have not heard of her being called for an IP. College may indeed be different. But she has had a good career carving up the local high school competition.