Recent Common opponent for Marquez and Pac is Barrera, Marquez struggled while PAC breezed thru. Coming in to this fight PAC is physically stonger and has a right hook as compared to his 2004 version, any changes on JMM I really dont see any aside from he will definitely respect PAC's power this time.
If a Green PAC gave JMM troubles before why can't he do it again this time, I see PAC winning this by decision like the MAB fight if JMM sticks to his counterpunching, if he decides to trade PAC stops him late in the fight.
I believe Manny can win this but I'm not betting on it