Cingrani has more talent, perhaps, but it's still very uncertain whether it will amount into better production than Leake. Despite the hang-wringing on this forum over Leake at times, he has a respectable 4.19 career ERA to this point. Cingrani has looked good, but there's no guarantee his talent will amount to even to that level.
I still honestly don't understand why everyone is so eager to replace Leake. I've said it before and I'll say it again, 90% of teams in the majors would kill to have a guy like Leake as their worst starter. With Arroyo coming off the books next year, there's simply no reason to be thinking about either/or with these two.