Corley wasn't anything by the time Cotto fought him, and he continues to be punching bag judging by what Devon did to him. I think Collazo is a fine stepping stone for Berto because he has no punching power. He was overwhelmed by Mosley, and Berto would do the same thing. I am not saying Collazo isn't a good proffesional, I am just saying that Berto doesn't have a whole lot of stepping stones left between him and guys like Collazo, Judah, etc.