Re: Juan Dinamita Marquez vs Miguel Cotto
The Marquez of the third Pacquiao fight takes a competitive decision over the 140 pound Cotto in my opinion. Both would have a lot of success, but Cotto's vulnerability to uppercuts and leaky defense would be capitalized on by Marquez and I see Marquez making more in-fight adjustments tactically, both offensively and defensively than Cotto. Cotto, towards the end of his 140 pound days, might very well get stopped too.
Marquez is simply a better fighter than Cotto. If they were both naturally the same size at their best, I think Marquez would tear Cotto apart with combinations, counters, and shots coming from underneath Cotto's stance/loose and "open up the middle" guard.