Jimmy Walker has made some significant changes for the better in his swing in recent years, although his penchant for pulling his head back a ton is still present. What has allowed him to improve his ball striking is a slight adjustment in posture to one more out over the balls of his feet, and a much different overall use of the right arm and the wrists in the backswing. Jimmy would normally have the clubface a bit closed and then pull his right arm behind him approaching the top, which would cause any full swing to cross the line at the top, which of course complicates everything in the forward swing. Now we can see that he is keeping his upper right arm more in front of his chest as he rotates his hands and wrists to open the face and keep the shaft more on plane as it approaches transition. All this gives him a better chance to square the face even as he pulls his head back 4-6 inches from its starting position as he impacts the ball. It just goes to show you that a talented player can time just about any type of swing pattern, but if you make the timing simpler that player will improve. Butch Harmon may be a one trick pony, but by focusing on right arm movement and width he has helped a bunch of already excellent players get better.