Well, it could be a few things. The weight of the ball is too heavy for you right now, which you can compensate for by lifting some weights. Also check the pitch of your thumb hole. If there is too much forward pitch, it could be making your thumb stick in the ball too long. Revs are created by the quick action of your thumb leaving the ball and your fingers rotating. The faster that action, the more revs. The last thing is to make sure the ball you're using is matched up to the condition. Maybe sanding your ball to a lower grit will help your reaction.

I know some of you people will say this has nothing to do with it, but whether you believe it or not, I shortened my RF 1/8" and both my accuracy and revs increased. If you go by the Bill Taylor method, my span should be 4 1/4 x 4 3/8 which it was. I changed it this week on my new Impluse Zone to 4 1/4 x 4 1/4 and couldn't believe the difference. Also more accurate on the corner pins that I miss 50% of the time.

This tells me that a person needs to go by what feels good and not by what Bill Taylor says. You can use Bill Taylor to start, but don't believe everything he says is correct, for years like I did. I have thought of making this change for quite some time, but everything I heard here and everething I read said I had the right span, so I couldn't seem to get up the courage to make this change.
This Bill Taylor suggested span worked better in the past, but apparently since I am now getting older and hands more stiff, it doesn't work, so I have to develop my own fit.