I've seen many photos of club hean 'droop' through impact. I'd alsways associated that with the fact that the club is inclined so the vertical component of the clubhead movement would produce the shaft flex.
However I now wonder about that. In this photo the bowing is in plane and you can imagine the force being resisted. I don't think this flex would just disappear in the next 0.06 seconds to impact, so the 'droop' at impact could be (also) related to the 'droop' developed in plane by deceleration and retention.
Since learning Bertholy, I now characterize Scott as a 'retainer' (clear trail arm 'Claw' one frame before impact!). Reviewing my video of him again I see that he also had noticeable shaft droop at '6/100s' (though clearly a shaft that is proportionately much stiffer than Nicklaus').
