Cotto would break him in half. Thurman can’t really take body punches and doesn’t have a defined style. He’d try to bomb Cotto early that would work and then he’d be on his bike but Cotto would break him down.
Thurman's movement is plentiful, but not the most intelligent. Cotto, on the other hand, is one of the best ring-cutters of the last era and possesses an educated jab, his pressure would herd and wilt Thurman and break him down. Keith can conceivably hurt Miguel with a single shot, but he lacks the teeth to put his guy away at this level.
Cotto is a very careful but dangerous fighter who combines good power and pressure with good ring generalship and timing. He's much more well rounded than Thurman who can only slug or get on his bike and throw 1 punch at a time. I think Cotto edges it on skill and experience. Both guys got marked up and swelled up a lot and both can crack when they let their hands go so a TKO win is definitely possible for either guy.
Only one who might get stopped here is Thurman. Thurman never stopped a top fighter. And he wouldnt start with Cotto. I think Thurman lasts the distance cause he runs. But he drops a wide decision.