[golfbulldog]

The pivot loads the #4 pressure point . . . .

There is more to this short answer than first appears...

The left arm moving across the chest in the backswing does not mean that the acc4 is being used.

3 barrel hitters left arm would go to "top"...left arm across the chest but the pivot would be minimal and would play no role in loading power package....only in creating a backstop for the right arm thrust. There would be no tight sqeeze of the "glove under left armpit". There is pivot motion but in a facilitating way rather than an motion driving way.

4 barrels hitter would go to "top" and uses pivot thrust to load acc4....squeeze the glove under left arm pit... then somehow add on right arm thrust ....

at least that is the only way I can square this apparent circle...

It would be interesting to see 3D motion analysis of these different actions but I think that the 3 barrel hitter could be spotted easily by the relative lack of pivot action...IMO