[BerntR]

The position Tiger is in there looks really damaging to mee. Hogan's move is better for spine & left knee and probably for ball trajectory as well.

Also note that AK saves his knee by flaring his front foot slightly open between the two frames. You can see a lot of that in Sadlowski's swing and also in Bubba Watson and a few others. They are however not snapping the knee. It is more like a running motion. Kick off the right foot, land on left, kick off the left foot. I'm more of a walker myself

Kelvin Myiahira has attributed the workings of the pivot to the "spine engine theory". He compares the footwork, the hipwork and the motions in the spine with what happens when we walk and run. It is very detailed on what happens between the hips and the arms, which isn't really detailed in the yellow book. But still 100% in agreement with the TGM notion that Yoda posted: "Hip Slide/Turn dictates Knee Action. Not vice versa".