Obviously Roy would be a massive favorite, does Cotto get Serwano'd here or does this go some rounds?
It ends literally whenever Roy chooses. And given that a middleweight Roy didn't fuck around when he had an overmatched guy in front of him, I'd say Cotto is a goner in 3, tops. Probably 2.
If this was an established Cotto of the last few years against a green Roy then possibly it could go some rounds. The only reason being Jones would be (at this fictional point) in the biggest fight of life and might be a little bit more mindful about biding his time. Wouldn't really matter if it goes 2 rounds or 8 as it would be one sided the entire time.