My name is Byron Toth, I am owner/operator of Toth's Score Mor Pro Shop, located here in Score's Fun Center in Painesville, Ohio. I'm a world record holder, I have multiple 300 games in 800 series and I'm here to talk about bowling. I'd like to demonstrate to you how to throw a bowling ball properly to get the proper rotation on the ball for the ball to hook on the lane.
Imparting the proper rotation on the ball and getting hook on the lane increase your entry angle into the pocket which increases your probability of striking when you hit the one three pocket. In order to do that, your fingers must, at the point of release, your fingers must be behind your thumb and somewhere on the side of the ball. It doesn't have to be in any particular location, depends on your bowler's and the lane condition that you're bowling on.
But when you release the ball, your fingers must be behind your thumb, and on the side of the ball so that when you come out of the ball it rotates. It's rotating like this down the lane, when it gets down the lane, the friction takes over and the ball starts to hook into the pocket.