Pac will break the shoulder roll defence of Floyd. Floyd's defense is a lean back position with shoulder roll to avoid gettin hit. While he does that, his body is in the position for Pac to hit. Pac will hit unlike other of his previous opponents. He'll break down the body, then work on the rest, the face. Floyd is pretty boy and has been. But I think Pac will tear him down. The only way he won't get torn is by running away all the time.
The reason Floyd always fight smaller man is because his style of defense will not stand a taller, longer-armed opponent. So far, his defense work on all the smaller or equal size opponent. But, it will not work on Paquiao for one reason. Pacquio's speed, punch power, and angle punch and foot work, combined with boxing smart, will break down Floyd's defense. It won't be easy easy fight, but I think Paquio will have edge if they both do fight.