It's foolish to think 1 pound lost cotto the fight and it's foolish to disregard skills & styles make fights. If cotto had to come down 10-15 pounds then yeah, maybe that's a big problem,but one pound ain't shit. Boxing isn't rocket science most of the time. Usually you look at both of the fighters skill-sets, and their styles and you can accurately predict who is going to win. Pacquiao beats Cotto at any weight from 140 to 154 not because of size (duh they are basically the same size) but because pac is a terrible style for Cotto to handle.
Did Pernell Whitaker, who came down 5 pounds to fight Julio Cesar Chavez Sr. struggle with the weight, or did he box the shit out of Chavez? Did Hopkins who moved down four pounds to fight Oscar struggle with the weight or did he knock him out? Did Hopkins, who moved down 5 pounds to fight Kelly Pavlik struggle with the weight or did he box the shit out of Pavlik? Seems like there is double standard here or a bias.
Throughout history, it's almost always the bigger guys who come down in weight who win the fight. Yet somehow when smaller Pac wins, he's criticized for beating the bigger men and new terms like "weight drained" are applied. One pound weight drained cotto, really? Why didn't 4-5 pounds weight drain Whitaker & Hopkins? Hmm, maybe it's because Whitaker was 10X better than Chavez sr ever was and Hopkins was 10x a fighter than Oscar ever was. Add to that Whitaker was a nightmare of a style for Chavez and so was Hopkins to Oscar (and Pac to Cotto).
Rather than discrediting wins over a measly pound, analyze the fighters. Analyze the styles, analyze their skill-sets, their strengths, their weaknesses. By doing this it's really easy to see why these guys won, despite any weight differences.
