Posted by: Jack Mankin (MrBatspeed@aol.com) on Thu Mar 1 00:10:48 2007

(Jack)
However, once the bat has been sweep back into the swing plane, there should be no further internal or external rotation of the lead-arm The lead-wrist remains palm-down and the elbow stays pointing into the swing plane.
#
(Tom)
I agree with this, BUT I do not think the bat has to enter the roughly 2D swing plane it fires to contact in until somewhat less than 4 frames before contact in high level swings which is somewhat after shoulders have tilted/been turned, .
#
(Jack)
It is the rotation of the lead-shoulder that pulls the bottom hand around with the arm suppling the linkage. Therefore, I would also have problem with claims that internal or external rotation of the arms rather than shoulder rotation that is the major power source
of the swing.
#
(Tom)
This linkage is driven by the unwinding of the torso with chp for last 3.5 frames or so to contact, but the earlier arm/forearm action assists in coiling the torso/separating the upper and lower halves as soon as the back elbow plateaus and starts down/as soon as
the front knee starts to turn the front foot open which is well before toe touch.
#

Hi Tom

Other than a frame difference in our analysis, I would say we agree after the terms we use are understood. Example; what you refer to as “the unwinding of the torso,” I call “shoulder rotation.” – Tom, it is the end of the month. I will open the new month with our discussion.

Jack Mankin