It's just a classic case of styles making fights. Quintana didn't become a different fighter since the Cotto fight, Williams didn't become a different fighter, or have any more trouble making weight, than he was/did against Margarito. Imo Quintana just can't take it to the body very well, and Cotto is a wicked body attacker in general. He get's sick leverage and power behind great kidney and liver shots.. Paul Williams can't punch half as hard. On top of that, Williams has huge lapses in defence and throws winging pitter pat shots, generating very little power in general, and especially little to the body. Quintana really didn't show anything more against Williams than he did against Cotto, Miguel just kept him a whole lot more wary and hurt him a lot more, as well as having the tighter defence. Quintana still was a hell of a slick boxer capable of landing his own shots and controlling a fight when he fought Cotto. Williams just isn't going to be able to do that well with good boxers if you ask me. Quintana was really the only guy he's faced who could move, counter and had any slickness.