You think that Byron's head would have moved as much is he was not elbow plane through impact ??
Both these guys like right elbow bend too!
Byron's head moves down because of the patented dippy knees . . . Hogan also had his head move down in the backstroke to. Certainly you want to have a "steady" head . . . but if you think about it this way if the hips go forward you head is likely to go down some . . . if you bend a stick the top of it goes down. I'm sure we can find plenty of examples of heads that don't go down . . . regardless . . . these two gentlemen flat planed the golf club . . . thru the ball the clubs don't deviate much . . . Hello 3 Functions . . . Meet Mr. Hogan and Mr. Nelson.