Nice video clip btw…
You are def. on the right track by focusing on how to get the hips to fire correctly to gain power in your delivery. When I teach lessons to my kids, the hip turn is one of the most important aspects I cover.
I will say, however, when I pitch and when I teach it, I don’t focus on firing the glutes and butt…that could easily lead to jumping forward and pushing off too hard. I think one of the most important things to think about is driving the back knee straight through the front knee as the back foot rotates and comes up out of the hole (to prevent foot drag). YOu want to stay tall and create height on your delivery to allow yourself to throw downhill. Alot of this comes from a properly executed hip turn. If you simply fire your glutes and “flex,” you will likely sink some on that back leg and loose the down angle that is so important.
Also, check out the timing between the elbows coming up and hips firing…You’ll notice his upper half stays on target a split second longer than his hips do…this is ESSENTIAL to translate the power from the hips directly into the release point of the baseball.