[EdZ]

No question he is a swinger.

The knee action has to be intentional in his case. If you watch the slow motion sequence, he is well up on the left foot at the end of the backswing, and has fully set the left knee/foot before much of anything else happens coming down.

Try the move - it results in what Schlee called the "World Class Move" - the flattening of the shaft, a bit like what you can see in Ricky Fowler's motion, and Sergio's as well. It also sets the right elbow in the perfect swinger's position, pitch, ready to be pulled on through.