[O.B.Left]

I have a very weak grip with the thumb on top of the shaft, which simplifies things a lot.

Then with that grip type a Purely Vertical Left Wrist Cock Plane of Motion could have a corresponding visually flat left wrist at Top. For golfers with "stronger" left hand grip types than Mizuno Joes "very weak" left hand a visually or literally flat left wrist Top can only be achieved via the introduction of some Horizontal Left Hand Motion......a less than ideal thing. Some "arching" say.

"Flat" in Homer speak is not necessarily literally flat .... The Left Hand at top must correspond to the grip type employed . Which for most means there's some degree of a " cup" present.

But here's my head scratcher: Given the above and assuming its desirable to have the left hand laying flat to the face of the Inclined Plane at Top , wouldnt this imply that there is only one Plane Angle available to the golfer absent any Horizontal left Hand Motion? Only one Plane Angle where he can cock his left wrist Vertically and get his Left Palm lying on the face of the plane?