Bobby Jones' backs wing was set up to strike the ball much further back than where he stood in relation to it.
If you watch Bobby Jones set up, he very cleverly addresses the ball with his right hand and hip instead of the left. When he takes his final address, however, you will notice a pronounced step back with the right foot.
Now, what goes up, must come down, and what goes back, must come back forward. So, during his downswing, you'll see the flaw manifest itself with that odd lurching of the right leg and hip into the shot...to get his right hip to where it was before he stepped back. That's also what caused the slight casting of the club into the ball, and the slight head-snap through impact. It was probably the best swing in the world for hickory-shafted clubs, however.
You'll find a great clip that illustrates my point here at YouTube:
Now, the problem is that Jones' step back, combined with his turn, put him in the perfect top. That was his rhythm. To take out that step back would have been to disrupt his rhythm, and so he lived with the flaw built into his set-up.
I believe he could have eliminated the flaw if he'd been willing to work to find the right set-up, but he was already so much better than everyone else, why would he have bothered? The game was already boring to him...
Now, if he'd had some competition...I think the final Bobby Jones swing would have been tighter. Out of necessity.
My humble opinion...