I'm also thinking this would lead to more shoulder pain than forearm pain. I can't say it's common, but I've seen it enough where I scratch my head and wonder what pitching coach is letting her throw like that (the ones I've seen have an even more exaggerated shoulder move - to the point where it looks like they're scratching their ear with their shoulder).
This is not how she’s taught. She is being taught the correct methods and does very good during practice and lesson. When everything is full speed she does fight the T-Rex arm. Things tend to get sideways during games - leaping instead of pushing off causing her to land on her front foot with a downward projection/arm jerk, etc. We can work on those things but we/instructor cannot get her to break the arm draw. I don’t want her to get hurt.What she is trying to do is to aim the ball. She has to trust her release. The reason the ball was going into the dirt is because she was leaning forward and she is short arming the pitch.
What I tell kids to help enforce the correct body position is she has to keep her brain above her butt. The head needs to be stationary and on top a straight spine. As soon as the head goes forward the rest of the body will follow.