I coach a 10u rec team with a couple of first time pitchers. Knowing how tough it is on rookie pitchers I began working with them last fall and through the winter in our garage.
I've got one girl who is really progressing nicely but she does the old mule kick with her pivot foot out towards first base after releasing the ball. I know this is fairly common as I've seen a lot of young pitchers do this and I was just wondering if there were any effective drills out there we haven't tried yet. She does most other aspects very well, she doesn't bend over at the waist, makes a good circle and has a nice follow through. Unfortunately, she frequently throws strikes when mule kicking so other than me telling her to work on it she's often getting decent results doing it.
So far, we mostly do dry pitches and work through the finish (legs in the "4" position then bringing the right leg around into defensive fielding position) but then she'll pick up a ball to pitch again and start doing the mule kick again.