This drill helps a hitter find the proper rear hip balance that is needed to hit in the high level pattern. Once a hitter performs this drill correctly he will feel and understand the 'drive train' and rear hip command and control. He will also experience the simultaneous unload of the hand pivot point and the rear hip pivot point.
I recommend you do this drill with front toss to get a feel for it. Once the hitter 'gets it'.....I highly recommend taking live bp with it.