Originally Posted by David in FL
How in the world did you come up with that, and more importantly, why?!
I assume you're referring to the four knuckle aspect of the grip, not to Sarezen's thumb out.
Necessity was the mother of my invention. I've always had trouble bringing the clubface square to the target line at impact. The grip I use allows me to keep the face square to the swing arc longer going back, and feels like (but probably is not) it's square to the arc up almost to the top (a 225 degree arc). The grip also allows me to feel like I am bringing the club face down square to the arc. When it feels square on the way up and down--whether it really is square or not doesn't matter, the face IS square to the ball at impact. If my hands are not massively rotated right at setup, I am not able to feel like the face is square to the arc during the entire swing, and, as a consequence, I don't strike the ball square. Hands in the neutral position, for example, at setup, make it impossible to take the face back square to the arc for more than about 30 degrees.
Having the square to the swing feeling for as much of the swing as possible means--to me--that the amount of forearm roll is minimized, which I think fosters a better ball strike. Many will disagree.
I doubt that this is a grip or swing that good players should try because release happens less fluidly than with the more orthodox grip, and that translates to lower clubhead speed. But, for those higher handicap players who struggle just to make a decent contact with the ball, and who care less about speed than they do about not shanking, hooking, or slicing the ball, it may be a viable option.
I love the swing, but it's only good for wedges and short irons.