How Do I Learn To Hit Down?

[Yoda]

What I'm interested in though Yoda, is the WHY....

---what is causing the club to bottom out before Left Shoulder? (and not AT Left Shoulder).

Just because the Club has hit the ground does not mean that it has reached its lowest point. That lowest point does not occur until the Clubhead is in front of the Left Shoulder (and further Down Plane, i.e., further down in the ground).

Low Point is established by the player at Impact Fix. Assuming the Ball is on the ground (or a low tee), if you locate the Ball Up Plane from Low Point, you will take a Divot. If you locate the Ball at Low Point, you will not.

Maybe the piece you are missing is this: When the Ball is located at Low Point, the Left Shoulder is automatically higher at Fix than it is with the Ball located further Up Plane, i.e., back in the Stance. This Shoulder-to-Ball Radius is established using the geometrically-correct procedure discussed in 2-J-1.