Cool thoughts, J. I would say that A leads to B and D... possibly C. What you see is a progression from stepping to pushing (an effort to get open) as the athlete matures. The emphasis was always static... when they were working on "the circle". Then... the need for a more dynamic movement arose... and the muscle memory of spinning to get open takes over.
I would partially disagree with your thoughts on A... Yes, that girl spins... but then pushes into ER ... and I think the people that try to work on fixing this... miss the more important concept. That concept is: the sequence of knee extension is being performed incorrectly.
A Crow-Hop is one of the harder fixes... no doubt...but if an athlete breaks apart their motion it can be fixed.
When I mention sequencing... I'm referring to the order in which the legs extend... and that extension is the straightening that takes place at the knee. Have a look:
and then have a look at Monica:
Many young pitchers make an association with striding... versus driving. If you're stuck in this little situation... ask them what stands out most in those two gifs? You might be surprised by their answer.
Then... consider these thoughts... comparing them to the gifs JRyan posted:
1) Which leg is doing more work?
2) WHICH LEG STRAIGHTENS FIRST?
3) Is either drive foot (Cat and Monica) twisting against the ground... or rotating as it pushes from the plate?
4) Does the heel of each drive foot travel OVER the big toe?
5) Did either pitcher 'open' in the gifs above?
Now... take those questions and compare them to what your daughter is doing... or the comparison gifs in JRyan's post.
Your goal is to convey the fact that in both Cat and Monica's examples... they STRAIGHTEN THE DRIVE LEG KNEE BEFORE THEY STRAIGHTEN THE STRIDE LEG KNEE. That's the sequence.
Now... take a look at that first girl... and tell me which leg straightens first? She's reaching out to a point... rather than driving out FROM ONE. That old saying: The plate is to push from NOT pitch from....
Both Cat and Monica PUSH WITH THE BIG TOE... and both have their heels TRAVELLING OVER THEIR BIG TOE, not around it.
Simply put: THE DRIVE NEEDS TO BE COMPLETED BEFORE THE STRIDE IS COMPLETED.
Thanks for your input J... really cool to see B again!
We are still having issues with this. DD spins off the mound and does not allow herself a chance to even push or to get her knee straight. She does the drills fine. Just when she does the full pitching motion is when everything breaks down. She still doesnt have the feeling of doing it the correct way. I have a feeling the sequence is out of order but I cant get her to realize it. When I show her video she sees its not right. Any thoughts??