Not to be rude by answering a question with a question but, if the backswing is making her inconsistent, why have one at all?
The glaring and obvious difference to me from the examples you showed is showing the grip of the ball to the hitter. From day 1 hitters are trained to focus on the pitcher's hit where the ball is released. When someone swings their hand back, the hitter gets 2 shots at seeing the ball and grip before it's released. I'm not in the habit of helping the hitter if I can avoid it. Anyway, I'm curious if you think this backswing is an ABSOLUTE or a STYLE for your daughter.
Bill
This is my original reply from March 27th
Not rude at all and a good question. She is currently loosing about 3-4mph without any backswing. I am not a person that thinks the backswing actually adds speed but she does get some kind of timing mechanism from the backswing that allows her to throw harder.
I do not think the backswing is an absolute. Too many great pitchers do different pre-motions differently for the backswing to be an absolute.
Here is an update fro today. She is throwing just as hard without a backswing one week later. It just took a little time for her to figure out a way to load her body without using a backswing.