One Planer
Global Moderator
OP - would look to earlier in the swing motion to help with the transition (which in lower body is all about ground pressure/force rather than weight shift or weight transfer) as what is/maybe able to happen from the top is a good bunch dependent on what's led into the top of the swing
if the 'turn away/upper body rotation' is a ways too flat it's very difficult to have the lead shoulder so lead arm move down without taking the head/upper body along too in that very first transition motion
the biggest area of flex bio-mechanically to the final piece of shoulder/chest turn to top is at the thoracic spine level junction + cervical (neck/head), the base of the spine much less flex there (as to why you see the kinda 'S shape' spine formation at the top in real good players - so the major creases across the 'lats' in the shirts )
if though the majority of 'turn' folks try to enable is from base of the spine the turn will always tend to be too flat
so first left shoulder movement would look to be 'downwards' & rotating back - rather than just turning back level
the arms can if wanted too, still work to match the plane of the shoulders at the top - it's just that the shoulder plane would be little ways steeper - then it's a bunch easier to get the separation at transition on the ways down from the top & not take the upper chest/head with it towards target to be ahead of the ball position
Is this basically starting down with the lower half while the upper half still coils?