Cotto is far from being done at the elite level. He actually has better defence and better boxing skills than he did during his days at the top of the 147 division. He is a different kind of fighter but in a good way the only disadvantage he has is that all the wars made his face easier to bruise so he can't take as much punishment.
BTW no one outside of Mayweather, Pacquiao and maybe Martinez can beat Cotto. Cotto would be a big favorite against all the other top guys from 140-160.