[Jeff]

OB left

You are correct that the TGM pivot axis (which is apparently a vertical line centralised between the feet while going through the base of the neck) is different to VJ's pivot axis. VJ has invented his own concept of a downswing pivot axis which is imprecisely defined. It starts at the left foot and goes up the left leg and then it is angled towards the center of the body. However, he states that the pivot axis changes constantly throughout the downswing and I don't think that he has precisely defined how it is angled at different time points during the downswing. He also states that the COG is near the navel. In his recommended backswing pivot action where the pelvis is shifted left-laterally in the late backswing, the pivot axis would then be very close to passing through his COG as it is situated at the end-backswing position. He believes that with the COG located near the pivot axis, that it allows a golfer to rotate more efficiently around his (idea of a) pivot axis without any need for a lateral pelvic shift in the early downswing. By contrast, Stuart Appleby would have to shift his pelvis left-laterally first in the early downswing (towards the left white line in those SA photos) before he could pivot in a rotational manner around this downswing pivot axis.

I personally have more sympathy for VJ's pivot axis idea (than the TGM vertical pivot axis idea) because i) at least he acknowledges that the downswing pivot axis is located somewhere near the left femoral neck, the pivot point for the pelvis rotation in the late downswing/followthrough - rather than being arbitrarily located centrally between the feet; and ii) because he thinks of the pivot axis as being angled from the left foot to the base of the neck (roughly related to the idea of secondary axis tilt) - rather than being vertical. I think that those two defining points make more sense from a biomechanical perspective, and I can relate to it better than TGM's vertical pivot axis centralised between the feet that goes vertically upwards to the base of the neck - creating a hypothetical tripod-shaped structure.

However, I cannot really relate to the idea of the torso being an unitary rotating cyllinder that rotates around that downswing pivot axis. I think of the "rightwards tilted spine and its angled relationship relative to the straight left leg" as being a braced skeletal structure (kept stationary by the stationary head) that provides structural support stability - so that the arms can swing efficiently and fluidly across the front of the rotating body after release of PA#4.

Jeff.