Leeson13,
Exploding your Lower Half is not an action ...
Exploding your Lower Half is a reaction to your Body being athletically stacked just prior to your Foot Strike and your Glove Hand activity triggering your Lower Half explosion.
To move into your Foot Strike athletically stacked, your Coach needs to teach you how to synchronize your Arm/Leg actions while on one leg. To make maintaining a single leg athletic stack easier, you want to move into your single leg phase from an already athletically stacked Starting Position.
You use your Front Leg in your Starting Position to keep your Head vertically over your Bellybutton. You essentially use your Front Leg to keep yourself balanced much the same way a tight rope walker uses his pole to keep himself from falling off his wire.
Your motion is a kinetic chain of events. Your first plan of attack needs to be your Starting Position. Ignore this and you may find your extra 5-10 miles per hour, but you'll lack the command needed to attract lots of Baseball Scouts.
L.A. "Skip" Fast
Pro Pitching Institute