Driving off the back foot
Lately I’ve been putting a lot of emphasis on driving the front knee out and up at launch. As well as that has been working, it’s important not to forget pushing off the back foot too.
The key thing is getting the timing right. You don’t want the feet to get too far apart from each other. That means the push off the back foot needs to come as the front knee is driving out.
Again, the object of all of it is to get the body/center of gravity moving forward effectively. This seems to be more difficult for some than others. I’ve observed some pitchers can push off strongly without much thought. Others will drive the front knee out, but just straight out or lock the back leg, which acts more as an anchor than an outboard engine when trying to get off the pitching rubber.
A good indicator is where the back foot is by the time the arm gets up to 12:00. By that point the back foot should already be dragging forward off the pitching rubber. A camera phone will show that. If it’s not coming forward the pitcher is not getting good back leg drive. You will need to correct that in order to maximize pitch speed and effectiveness.
Video is one of the best allies in this one. Show the pitcher what she’s doing, explain how to change it, and work on that foot work. You should see an improvement in speed in a short period of time.