mb6606
You sent me a link to this video of Jason Zuback's swing which has a number of slow mo sections.
I made the following series of images of his downswing
First of all, regarding the clubshaft. I see this problem of double images frequently - even when examining slow mo videos. This makes it difficult to know what is real versus camera distortion. Image 4 shows two images - one of the images has forwards shaft lean. Image 5 shows double images at impact with the shaft bent back in the one image, which would be expected post-impact.
I therefore do not know whether Jamie Sadlowski's forwardly bent shaft post-impact is "real" (possibly due to using a more flexible shaft) or due to camera distortion.
Secondly, look at Jason's swing. He has a centralised pivot action, and he reverse pivots slightly with a large hip turn (like Sam Snead) by the end-backswing - image 1. Note how he then has to reverse his spine tilt in the downswing so that he acquires a rightwards tilt-secondary axis tilt in the early downswing - image 3. I don't think that it is a biomechnaically efficient action. Note how he loses his clubhead lag angle - image 3. I think that it is due to the fact that he has to throw his upper torso and therefore arms backwards (away from the target) at the start of the downswing to reverse the spine tilt. The reversal of hand movement (going backwards away from the target) predisposes to an early release.
Here is another example of that phenomenon in an excellent golfer.
In the first swing, he reverse pivots slightly. Note his loss of clubhead lag angle. In his second swing I think he has a better pivot action with a reverse-K look, and a much better retention of his clubhead lag angle in the early downswing.
That's why I prefer Jamie's swing over Jason's swing. Jamie has a traditional swing with a reverse-K look at the end of his backswing, and he retains his clubhead lag angle well into the downswing.
Jeff.