Great question....
As the club goes back it has to be slowed, then stopped, before it can change direction.
Imagine a car that starts to slide rewards on ice....a few of us run over to the rear of the car and start pushing it forward. At first all we do is slow the rearward slide. Then, we overcome that slide slowing it to a halt and then successfully changing the direction of the vehicle.
Same thing in golf.
As the club moves toward the top of the swing (negative alpha) if that forward torque (positive alpha) is applied soon enough and smooth enough, the club will change directions smoothly.
If not....like a sudden positive alpha....BOUNCE....or no (or very little) positive alpha.....then it will bounce off the hands or sometimes....the neck or shoulders.
Ouch!
