@Roger has hit the nail on the head.
Your leg lift potential energy is completely neutralized by the leg drop before moving toward home. As a result you are very slow with the lower half, delivery, and velocity. Your body’s acceleration window is very short, so everything done with the lower half has to take maximum advantage of what little time there is to stockpile energy. For as much good as your lower half does you, you may as well pitch from a chair.
Powerful, quick=explosive. Once you get to the top of the lift, if any motion is neither of these, it doesn’t belong in the delivery.