The key to taking a great shot, is strong legs that remain steady whilst the brain recovers.
That's my one thought about Floyd advancing in age, a boxer's legs lose a little something - but he is still supremely fit - and has good enough power of his own to take out Manny with a flush shot to the chin.
Manny will need to keep changing the game plan on the fly, because Floyd is great at adapting to recoup the advantage. Aggressive raiding tactics by Manny will be what Floyd is expecting, the key for manny is to keep constantly mixing it up stylewise.
At the end of the day though, this is a stale fight. Without sounding like another broken record, this is five years too late in my opinion.
Pacman made Cotto looked like chopped meat and left devastating eye-socket injuries to Margarito, whom Manny couldn't miss. His accuracy in that fight was likely his highest. But the KO's have certainly dried up for Manny in recent times, fighters like Tim Bradley are tough and expected to go 12 rounds, but Algieri and Rios should have been dispatched in their first foray into the welter division by arguably one of the best in that division.
Floyd doesn't like southpaws, that's a well reported fact that has dogged him for ages. He's also going to be facing someone with feet as quick as his too.
I believe Floyd will pull out the win, but will be a tough fight style-wise for the 38-yr old fighter.