Watch the rotation, the ball will rotate at some angle to straight with the boards as the ball hooks, it starts to move in the direction of the rotation.

As the ball hooks it loses it's side rotation and begins roling end over end in the direction of the rotation. It is at this point that you want the ball to hit the pins.

After this point the ball starts to rotate in the direction of the boards, at this point the ball has burned up or hooked out and will hit the pins too weak and leave you a "weak" 10 pin where the 6 pin is laying in the chanel, or a pocket 7-10 or a pocket 8 or an 8-10. That is why it is important to watch the ball all the way through the pins.