Maintaining lag pressure thru impact helps to maintain control of the club. The loss of lag pressure prior to impact results in a loss of control of the club. If you are trying to finesse the club, you would think that you would need to have total control of the club for such a delicate shot?
Terminology is a problem here. If I understand you correctly your idea of control is tied in with the idea of the hands leading the club. If overdone that makes it impossible to play a model Sieckmann style finesse shot. One way to put it is that where a little lag pressure at impact might be a good thing on these shots more lag pressure does not necessarily make for more control.
In my mind Sieckmann advocates mechanics something like the impact you would want if you swung a putter back and through to waste height neither wanting a downward strike nor an upward strike. The shaft lean is almost zero at impact, goes to zero an inch or so after impact and then goes negative after that (of course that changes if you want to hit down on the ball as you may well do).
The power sequence is thus reversed with maximum lag pressure at the start of the down stroke to ensure that the club catches up with the hands (although Sieckmann talks about the club falling due to gravity which I think is wrong). The lag pressure decreases to zero or close to zero at impact. The key control technique is to keep the club, hands, arms and shoulders and even hips moving together through impact but with no acceleration at impact. To switch analogies it is a bit like playing a shot with a shaft that turns to rope about a foot before impact.
This reversal has been demonstrated by testing of players by TPI. After "discovering" the kinetic sequence they couldn't understand what they were seeing on finesse shots. It was Sieckmann's ideas which enabled them to understand.
FWIW I don't subscribe to all of Sieckmann's ideas. I think the pure finesse shot he describes is as much a fiction as a pure pendulum putting stroke. But I do find it helpful to get rid of lag well before impact. The opposite of downcock is a good thing on these shots.
Edited by Forrest Gardener, 17 October 2018 - 12:38 AM.