[Yoda]

It's clear to me that the guys in the top row all have the problem of the misguided concept of striking the ball while the shoulders are square to the plane line. They've stopped turning their shoulders in order for the hands to catch up and the only way for the left wrist to remain flat is to accelerate the left wrist targetward by moving the left arm away from the body(overacceleration/independent hand/arm motion). Look at the billowing shirts above the left shoulders in #6,8,9,10 as their shoulders turn through the shot.

Good observation, MJ.

Note the "comparatively Squared-Away" yet still slightly Open alignment of the Shoulders in the Standard and Special Impact Fix Variations (10-8-A/B photos). In Pivot Strokes, the Body Rotation ideally Loads the Lag at Start Down and then continues to lead the Arms and Hands throughout the Downstroke.

However, this desired Body Rotation must not be allowed to pull the Club Off Plane (Bent Plane Line). Hence, our Hand-Controlled-Pivot System and the necessity of Plane Line Tracing through Impact.