[Yoda]

Mr. Kelley always drew diagrams like this according to general engineering principles. The dashes are always the preceeding location of the solid drawing, similar to drawing up blue-prints.

The Sweet Spot Plane is the Plane you should be concerned with. It is the Sweet Spot Plane, not the Clubshaft Plane that lies on the flight line or target line. The clubshaft does not remain on a constant Plane, it rotates around the Sweet Spot. The Sweet Spot is trying to get in line with your #3 PP so you can use it to trace your delivery line while sensing Clubhead Lag (actively for a Hitter, passively for a Swinger).

Great post, Drew. There is much 'meat' here, especially for such a short post. I recommend a very careful reading.

Then, read it again.