So, how is a proper peel drop thrown to make best downward movement?
First off the angle of release (down) is most important. That is why "pulling up" on the ball is not advisable because all you are trying to do there is just get spin. Spin is only half the equation. As Bill puts it, it is the snap of the elbow then wrist then fingers which are behind the ball which will then impart the spin and the speed of the ball. It is more of a push behind the ball in my opinion which generates the spin. Quite simple and natural to boot. Pulling up requires the body to do other things and disrupts the smooth flow of the pitch.