Arguello was a better fighter than JMM, who isn't the type of pure boxer/mover that could outbox Alexis. JMM, as tough and resilient as he is, would get stopped imo.
The fact that JMM has a rock solid chin and terrific recuperative abilities probably turns into a negative in that one.
I really don't recall him being stunned at any point. Simply struggling with the sheer volume. When was he stunned?
I'd have to see it again but **** Ottke knocked Mundine out cold and Malignaggi stunned Diaz. Proves little if he was stunned.
Arguello's height and reach would make it difficult for Marquez to play the counter puncher. You can't counter what you can't reach. Marquez would have to step in to counter, and Alexis WANTED guys to try and step in on him. AA's height, reach, excellent timing, and heavy hands add up to a KO. Probably mid-rounds.