I think this is yet another term that means different things to different people. It dawned on me today that actually the term does have some useful meaning if understood properly. It has to do with Nyman's top hand "rabbit punch", except that knob to the ball would be more accurate.
Knob to the ball, if incorporated very early in the swing (like at toe touch) will enhance elbow-in-the-slot and for that matter it will facilitate the technique that I think you all refer to as top hand torque.