It depends. Pacquiao gets lazy in the later rounds, especially when he builds up an early lead. I could see Lopez outworking Pacquiao in rounds 6-15, barely squeaking out a decision. Pacquiao's the favorite, but only by a small margin.
Anyone who's followed Pacquiao's career knows that his dedication to boxing is nowhere near what it should be, given his talent. At least when Roy Jones played basketball during training, it improved his cardiovascular strength. Playing pool all the time? Bleh. It cost him a win against Juan Manuel Marquez, and no one's going to convince me that Pacquiao's nearly as good in rounds 7-12 as he is in rounds 1-6.
I think Pacquiao's speed and southpaw stance would just be a little too much for Little Red to overcome Bear in mind, Lopez had more guts than sense and could hit like a bastard, pacquaio can't just do whatever he wnats in there. He has to think a little bit more defensively than he typically does. But still, barring the turn-it-all-around type of shot from Lopez, I like Pacquaio to stop a bloodied and game Lopez late
see. i'm thinkin the exact opposite. when Chacon got in close and flurried, that's how he beat Lopez up. it's on the outside, from distance that Lopez was dangerous. he could throw upper-cuts, and fight inside a little, but usually those he used to set up his long shots - those were the ones he killed with. if you could back Lopez up, he was lost. And not only Pacquiao's speed, but his angles would keep Lopez confused who has to be set to punch. this fight would not be all that competitive IMO.