It seems like his left thumb almost raps the club at times as opposed to running down the club. The picture below shows it but ive seen it other places too. Like the video
Does anyone know what he is doing?
The picture on the left is Phil at address. The picture on the right is Phil at impact. His thumb is fine at address, but wrapped at impact. The thing you don't see in that picture is that the inside of his left hand comes off the club / inside of right hand during the swing, and when he gets it back on it is not in the same place. I used to do the same exact thing and it took me a long time to correct this swing flaw. I did it by placing a dollar bill between (I am right handed) the thumb pad of my left hand and the lower pad below that of my right hand. I had to get used to making a swing without that bill falling out.