Manny's speed and quickness would keep him a step ahead early but I just don't trust him to hold up when he gets hit and yes Cuevas would land on him. And when he does, I see Pac crumbling.
Cuevas was a robot. He had no defense and could not fight going backwards. Pacman overwhelms him and eventually stops him within 6 rounds.
Cuevas has a live punchers chance for as long as it goes but the odds are on pacquiao not staying still long enough to even let him get into the fight. The difference in mobility and 'trigger speed' is about as big as any match up between good world champs you could name Itd look like a higher quality tua fight....and similarly it might just take one moment to turn the tide