Neil: You will probably find the issue in the grip! The sublety you mention is, I suspect, in having, at setup, the dish angle in your left hand--hence low hands at setup, and then maintaining it as you go back. This permits the loadup in your hands that might only be 5* more, but which is responsible for the differences both in feel and distance. Just as you say: it is elusive, and not because your modd changes or something irrelevant: it is in the critical position.
Remember how Hogan's "other secret" of his cupped left wrist at the top was revealed AS a secret? Cupped is a relative word. Talking about Tiger's current work with Haney, someone mentioned he heard Tiger say, pointing to the dish angle of his left wrist, that he was working on KEEPING THAT UNCHANGED during his swing. So keeping it unchanged to the top enables that critical extra foldback that is not possible if the wrist gets bowed in an attempt to "flatten" it - flat does not work for everyone (Daly..)
THEN, in the downswing, no deliberate rotation need occur and the pivot applies its power without any leakage and you definitely "feel" the club - it's impossible not to sense its massiveness.
Which you drive into the ball.
Betcha.
