[Jeff]

Pistol

It is my biased opinion that you may have problems with respect to understanding cause-and-effect relationships in human biomechanics.

You seem to have difficulty understanding how a fast hip turn at the start of the downswing can cause the clubshaft to shallow-out/flatten. You also seem to have difficulty understanding how a flattening clubshaft at the top of the swing can produce forces that promote left wrist flattening. You state that a fast hip turn can increase cupping. It can if the clubshaft is kept across-the-line. However, Hogan's clubhead moved backwards (away from the ball-target line) so that his clubshaft became laid off at the start of the downswing, and that clubshaft movement makes it much more difficult to maintain a cupped left wrist. In fact, that clubshaft movement promotes the passive acquisition of a flat left wrist.

Also, whether a golfer decides to allow the left wrist to be flattened in response to forces that shallow/flatten the clubshaft is still under control by the golfer. It is obviously possible for a golfer to deliberately resist those forces and intentionally maintain a cupped wrist.

There is a second biomechanical phenomenon that promotes a flattening of the left wrist when the downswing starts with a fast hip shift-rotation movement. That fast lower body movement also causes the right elbow to be pulled rapidly down towards the right hip area, and because the right arm flying wedge remains intact, that right elbow movement causes the right forearm and right hand to be pulled down under the flattening clubshaft, which in turn promotes further flattening of the clubshaft - as can be seen in this photo.



Whether you find my biomechanical explanation credible, or not, the photos demonstrate the "reality" that Hogan's left wrist flattened at the start of the downswing, and this biomechanical event would cause the clubface to close slightly if the left wrist was previously cupped.

Jeff.