[no_mind_golfer]

So, regarding your "beautiful theory", are you suggesting that the rate of closing is always constant in the Downstroke?

Instead of having "nothing" to do with Angular Momentum, would a delay in the closing have something to do with Angular Momentum and/or an axis of rotation?

I'm not suggesting anything is constant in a real golfer... but yes.. the gears make the rate proportional to the arm rotation angular velocity and.. its not my theory gone bad .... its yours Yodasluke.

As I was thinking about issue this I asked myself: why would they would they design clubface rotation into the swing machine since it complicates the machine (one more DOF to contend with). I made a call and the answer was because that was the way Byron Nelson (the model) did it and also because they found they needed gearing there to help manage the deceleration. (It took Battelle 3 years to develop the iron byron and initially they were breaking a lot of shafts). Then I asked myself why does iron Byron Nelson and everyone else fan the face open on the backswing? The answer to that is... TRY IT. You can't not.

As far as leaving the face open at impact goes (delay in closing?) bottom-line is golfer's left hand is not getting back where it was at takeaway.

Many golfers look a lot different at impact than they do at setup... hands may be way forward... shoulders too open or too closed etc. They can compensate for different impact positions by intentionally (closing usually) the club face at set up. (You would be amazed at how "toe-in" my dad sets up with his driver but it works for him... he's ALWAY down the middle) That way when they get back to impact the face is aligned where they need it to be.

Get the back of your left hand back to facing the target at impact (like it was at se-up) and your club face will be fine......