[Mathew]

Mathew,
By "work against the onplane pressure of pp3", do you mean it exerts force against lag? Just trying to clear the fog. I understand and am clear on the rest. Good post.

The force of extensor action with pp3 does not move the left arm and does not create clubhead lag - the stressing of the shaft.

PP4 works against the onplane pressure of pp3 until the spine tilts so that acc4 can thrust pp3 down the plane line. pp4 is trying to move the lever assembly out and pp3 is work against pp4 thats trying to take it offplane, the only way acc4 can move so that pp3 can trace that plane line is if the spine tilts and that right shoulder goes downplane.