[EdZ]

"prior to the low point of the Downstroke" can be regarded as "prior to the shaft being in-line with the leading arm", which also means "prior to release (throwaway)" when the pivot is vertical to the ground.

The clubhead can pass the low point and start to move upward (relative to the level ground) at impact "prior to the shaft being in-line with the leading arm" or "prior to release (throwaway)" when the pivot is tilted away from the target. The ball needs to be teed up to allow the above to happen without hitting it fat.

Hackers usually hit the ball "after the shaft passing the in-line condition with the leading arm" or "after release (throwaway)", regardless of pivot position.

Excellent post!