[bts]

Pivot alone will not get the hands in the correct onplane position at the top of the swing...I would think that it is primarily the responsibility of the hands supported by the right forearm. The right shoulder turns to the plane.

Instead of you, the pivot rotation powers the arms and hands, which powers the club, of which momentum creates the right wrist bent, left wrist cock, right arm fold and both forearm rotation, all perfectly on-plane.