Scott;
As always - a terrific-ly (?) well stated explanation. My HS son is a habitual bug-squisher unless I point it out to him. Then he corrects and becomes more Pujols-like. The original sit-back and swing process started with Epstein, but then turned slightly and became his own deal. He has good power and hits the ball (baseball) well, but we always know he has more power and control when he is rolling onto the toe rather than grinding it.
What we've found is that when squishing (I tell him to quit spinning), the force that could go into the bat velocity is instead wasted on his back knee and the friction on the ground. We have some excellent photos from over the years of players "tilting" back, but one can see 1/4" or so of air under the back foot as momentum carries them against their front foot.
With regard to the know, I also have continually noted the exceptionally light grip on the bat with both the top hand as well as on the knob. Loose fingers as I coach the girls.. I supect that having very little contact with the bat makes it quicker, but gripping it at the knob also lengthens the bat and maybe provides a tad more speed in the barrel at contact.
Thoughts?
-curt