When I cup my wrist for extra revs (normally, I hold it straight) I find that I tend to come around the ball a lot, so that the extra revs are paired with more side rotation - it seems as if I cannot keep my hand behind the ball when I try this release.
That said, maybe there is an additional influence in your delivery that makes you hold onto the ball, e. g. a bent upper body, or another timing issue.
Another idea: a local player (and trainer) once told me that changing the wrist position can have effect on the timing, because the point where the thumb exits the ball (or should do so) during the swing changes. My suggestion would be to try to start your pendulum a tad earlier than usual - the idea is to have the ball back into your normal timing, despite the slight release point change.
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DizzyFugu - Reporting from Germany
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