Your thumb, your middle finger and your ring finger go in the ball. But that doesn’t mean your other fingers are useless. In fact, they can be very useful.
How to Identify A Need to Move
If you need to put more hook on the ball or take some hook off the ball, one of the simplest ways is to alter how and where your index and pinky fingers rest on the bowling ball.
Keep in mind, this is a general guide for beginning bowlers. Advanced bowlers may use these same tips to achieve the opposite reaction. As you experiment with different finger positions, you'll naturally develop an ability to know how your ball will react.
How to Execute the Move
When you want less hook, spread your fingers wider. This restricts your ability to put the spin on the ball with the fingers in the ball, and results in a straighter shot.
Conversely, if you want more hook, bring your fingers closer together, which gives your middle and ring fingers extra reign over putting spin on the ball. You can also tuck your pinky finger to the first knuckle, which will promote more hook.
How Often to Adjust
Once you get a good feel for how these subtle changes can affect your shots, you might find yourself altering your finger positions from shot to shot.
In general, you should adjust any time you need more or less hook.