[Jeff]

I cannot understand why the left wrist has to cup excessively when the left hand moves down from its end-backswing position to the impact position in the downswing.

Here is a link to a swing video of Stuart Appleby swinging on plane.

I have made a series of capture images of his downswing.



Isn't his left hand essentially flat throughout the downswing? The left hand in the second image may be slightly less flat than the first image (start of the downswing) only because his left hand is minimally less palmar flexed, and I think that a small degree of left wrist palmar flexion is necessary to have a perfectly flat left wrist.

Jeff.