Looks can be deceiving. The purpose of getting to, and continuing with, the motion that sits on top of the stride is to accelerate, and continue with the release of the ball … which is all part of a “release phase” rather than a “release point”, as it’s sometimes called.
Explosive forward movement is the life blood of sound pitching practices, and the end result is releasing all that energy to the ball … as it blisters down range to the catcher. And that statement also pertains to more than just the pitches in the fastball family. This also pertains to all your pitch inventory, even your off-speed/change-up.
I would like to draw you attention to the knuckleball, with respect to my last statement. Although the knuckleball may not look like it gets it performance in part from the same drive forward … it does. But the pitcher is not in a firepower posture with his/her entire body per say. Nevertheless, the same cycle of platforms apply -legs, hip, torso, and shoulder platforms.
And by the way, the “fluid” part of explosive motions, is the fact that the fluid is just moving a heck of lot faster than the name “fluid” would imply.
Good question and well thought out.