update:Keep it simple. Make her WHIP her elbow to the point where the hand nearly finishes to the OPPOSITE shoulder just to get that feel. After that, the spin will be straighter.
I'm glad it helped. Keep it simple. Remind her too that, pitching is just like hitting. Whenever we TRY to hit a homerun, we never do. But being relaxed in the batters box is when it happens. Pitching is the same. The harder you TRY the worse result.update:
we have been doing alot of underhand throwing focusing on whipping her elbow. keeping her arm loose. Also doing some relaxed walkthrough long toss, working out and and then back in.
what is amazing is that the ball is zipping out of her hand with the correct spin! This completely fixed her spin rotation without even focusing on that. (All our balls are taped from when we thought we should be working on that.)
We haven't done much full pitching from the mound. But two days ago we had a pitching lesson and DD was hitting 46 without much effort continually. She was really surprised since it felt really effortless. So, I think we are on the right track.