Mayorga won't win over Mosley if he did then definately Cotto's win would lose a little bit of luster.
Mosley hasn't been anything special since he lost to Vernon Forrest nearly 8 years ago. He went on to get a NC against the washed up Raul Marquez, then he received a gift decision against DLH, he then lost two more times to Winky. He went neck to neck with a very shot Vargas, only to win because Vargas got swollen, and then another win against an even more shot Vargas. He was rocked by Cruz and couldn't put him away, still managed to win even though Cintron destroyed the same fighter, he got a decent win against not so highly regarded Collazo and lost to Cotto. Has not KO a worthy opponent since 2001 in his last 13 fights.
Despite the fact that Cotto was the favorite over Mosley it seems like Cotto benefited tremendously from low expectations in that fight. Cotto has become "one of the most skilled boxers in the sport" all of the sudden in large part because of that win. Literally, before that fight, only a very small number of hardcore Cotto fans would speak about him in terms of being skilled because they had seen all his early fights. To everyone else he was just a body destroyer and a rough-house. Now Cotto is the Puerto Rican Sugar Ray Robinson, and it's virtually an overnight thing. Personally, I don't see how the Mosley win couldn't go down as one of the most overrated in the history of boxing in 100+ years. Shane looked like someone without a life-preserver unable to swim at different points. Forget about him being old or shot - he looked utterly lost, confused, and possibly semi brain damaged in that fight during repeated intervals. I already don't rate it very highly as a win. Waaaaaaaay too much hype. Cotto was supposed to beat a 100% Mosley, he ended up beating a shell of Mosley.
Mosley hasn't even been half of what he was when he beat DLH since the Forrest fights. I truly believe Mosley has become one of the most overrated fighters of this era. Really aside from having a close clear win against DLH in 2000, what else has he done since moving up to 147+? It's been 8 years and 13 fights later and he is yet to beat an elite fighter. He hasn't even been able to KO B- fighters in 8 years! He has no jab whatsoever that he made Cotto's jab look like ODLS or SRL's, he throws one punch at a time, and is flat footed and stationary.
I expect Mosley to win but wouldn't be surprised if he didn't. Mayorga is a style buster, not so much a great boxer. He can make you throw your game plan out and can overwhelm you. He's underrated imo. It wouldn't take away from Cotto at all since it would be a question of styles not abilities. Forrest was a fine boxer. His loss to Mayorga doesn't take away from that.
Then Cotto's win over Mosley would probably lose some credit.. I don't expect Mayorga to even have a chance against Mosley though.. Isn't the fight suppose to take place in october and are they still talking ppv?