Andretti: Flipping = Loss of Lag Pressure before you have made contact with the ball. Ideally you want that feeling of lag pressure maintained until both arms are straight in the follow-through. Monitor lag pressure with your trail finger where it contacts the grip . If you lose lag pressure there in the downstroke you have flipped. Overacceleration can lead to flipping so work on a steady constant acceleration and rhythm from the top to past the ball and don't get ahead of yourself
But I wouldn't say that it's loss of lag pressure- even if I'm sure it is, by definition.
When I say 'flipping' I mean more like 'whipping' with the hands. But it is a deliberate forward motion of the clubhead that kicks in after the hands have reached of passed the ball. I would even say that it is my no 3 ppt that is applying the pressure.
Hmm.. I guess the shaft isn't all that stressed in this condition, but I reach a MUCH greater club head speed this way.