His family look tortured every time he fights. I'd guess that has something to do with it, aside from it just being the right time to say goodbye. I've never been too keen on Cotto as a personality, not to mention that he was horribly overrated between November 2007 and July 2008, but he's earned an eminently winnable swan song and retirement. And I'll be darned if he couldn't cut a ring off with as guileful an economy of footsteps as any in his era.