Here's where I'm at in my self-discovery.........An object, like a clubhead, or a point on the grip, which is swung in a circular arc, will reach its lowest point when it lines up its center of rotation. If the hands are swung STRICTLY by torso rotation, the they will reach their lowest point when they line up with the upper sternum on the plane of the hand swing, because that's the center of the torso rotation. And great players are leading the club into impact mostly with torso rotation, and perhaps minimal forward left arm swing from the left shoulder joint, explaining why the lowest point of the hand arc is being found to be in-line with a point that is near the upper sternum. IF their was no bending of the left wrist approaching impact, then the clubhead would reach ITS lowest point when it also lined up with the center of the system which was rotating it. This would be at the same in-line point as the bottom of the hand arc, but by the time the clubhead reaches that point, the hands will be well past that point and on their way up, assuming that the clubhead is properly behing the hands. BUT, and this is a BIG BUT, the clubshaft is ALWAYS unhinging from the left arm approaching impact. The Conservation of Angular Momemtum tells us that as the energy is passed to the clubhead in the final stages approaching impact, the hands slow. And the movement of the clubshaft just before impact is almost entirely from the wrists. The location of the axis of THIS system of rotation, at the hands, will have a HUGE effect on the ultimate location of the lowest point of the clubhead arc. The farther along the shaft has unhinged at the wrists by impact, the less descending the Attack Angle will be, when the lowest point of the hand arc is constant. If their was only one system of rotation which was swinging the clubhead, then locating the lowest point would be simple.......it would always be in-line with the center of rotation. But ALL of the axes of rotation.....uppers sternum, left shoulder, and hands are influencing the ultimate location of the clubhead low point. The location of the axis at the wrists is HUGELY influential and as important as ever.