>>> What if we substituted "shoulders" for "hips"? "Think about driving your back shoulder through the ball and at the same time pulling your front shoulder back towards the catcher at contact."
Would that cue work? Or am I barking up the wrong tree here? <<<
Jack Mankin's reply:
Now you're barking up the right tree. I think you realize that for hip rotation to have any effect on bat speed, it must result in shoulder rotation. The energy from hip rotation can only be transferred to the bat via the rate of angular displacement of the shoulders. But even full shoulder rotation does not insure that the batter will be in a position to develop good bat speed, which requires applying bottom-hand-torque.
For shoulder rotation to produce the "hook" effect (bht), two important conditions must be meet. (1) The lead shoulder must continue pulling the lead-arm back to, and slightly through, contact. (2) The bat must be brought to contact before the back-elbow extends out of the "L" position.
Hitters exhibiting Good & Poor BHT
While doing "swing reviews" I see a number of hitters with full hip and shoulder rotation that generate little bat speed. The problem is, they complete body rotation 1 or 2 video frames before the bat is brought to contact. Having completed rotation with the bat still 40 to 80 degrees from contact means the back-arm will need to extend farther and farther to bring the bat through.
There is no way a batter can produce the "hook" effect (pulling back with the lead-arm) with the back-arm nearing full extension. --- For the batter to be in a position to apply bottom-hand-torque before (and to) contact, he must have good "linkage," and apply top-hand-torque at initiation.
*** If the batter does not initiate the swing with the correct forces (including tht), he will not be in a position to apply bottom-hand-torque at contact. This is true regardless of how much hip-to-shoulder separation he has. Note: A hitter may be able to start with a static bat and still apply bht if the pitch is inside. But as the pitches move farther out, the more tht is needed at initiation.