I actually increase revs with speed as long as I follow through. I know some don't increase revs with speed.
Since I didn't see you bowl so I don't have a visual answer, like someone said, timing and timely thumb release will help your rev rate. If your thumb stays in the ball too long, it will be difficult to increase your rev rate. My Son gets the ball down on the lane very smoothly, too smoothly most of the time. Leaves a lot of 10 pins. He's 17 and doesn't take advise very well. But when he asks, I tell him to loft the ball 121-18 inches, keeeping his hand under the ball and coming through it just like he does for his normal release. When he does that, he can see his rev rate increase and carries the 10 pin much better. But on the other side, if you loft your ball to much, your thumb might remain in to long preventing you from putting the revs you wnt on the ball. So timing and hand position upon release is very important.
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Nicanor (Ten On The Deck)