[O.B.Left]

The palm of the Left Hand does not lie in the plane of the Left Arm when the Left Wrist is Flat (upper Left Arm in line with the back of the Left Hand). Because of the heel of the Hand, it is sloped away from it (counterclockwise) and appears 'more vertical' at the Top (and In Line with the Plane of the Turned Right Shoulder). Thus, the Wrist can Cock on Plane without the Left Arm being On Plane.

Maybe what you are considering the Vertical Wristcock Motion of a Flat Left Wrist is really the Vertical Wristcock of an Arched Left Wrist (which puts the palm in line with the lower part of the Left Forearm and therefore not On Plane with the Right Shoulder).

Yoda

I just read this very interesting thread from long ago. This may be slightly off the original topic but can I ask you a few questions regarding the vertical plane of the left hand cocking and un cocking and the associated club face alignment.

-When hammering in a truly vertical manner does the club face stay vertical and parallel to the left forearm (assuming it was so aligned at the start)?
-When moving this vertical action to the inclined plane does not the club face stay similarly aligned to the back of the left forearm?
-If so then is the face not laying on the plane of the left arm rather than the turned shoulder plane or the hands plane?

I can see how the left hand bends to the shoulder plane as the player approaches top or end but am confused about the club face alignment in regard to the inclined plane at top or during release swivel or finish swivel too for that matter (back on topic)

Regards
O.B.