[Mathew]

If the pivot tries to add - above and beyond, alignments and rhythm suffer.

If the pivot supplies the power and one cannot add with the hands what good is extensor action??
The video of Homer swinging quote, "coming down on the ball as if to drive it into the ground". No mention of pivot only the hands driving the ball into the ground. The pivot follows the lead of the hands going down and out.

This is my opinion on the matter...

For the swinger using pp4 as the direct thrust to drag the primary lever assembly. The pivot is doing the work via the direct thrust of pp4 but it is guided by using pp3 (or rotated lag pressure point equivalent) which is used to monitor plane alignments.

pp4 does the work
pp3 guides

Homer was referencing just merely the geometry of the circle and how you still have to go down and out through impact... IMO