My Mexican source tells me Alvarez does have some irish blood which most likely came from the San Patricio (St Patrick) battalion which fought alongside Mexico in the 1846-1848 war against the US. Another source says his mother is irish. Guadalajara was the base for the battalion and its bloodnut central down there. Michael Hogan has a good book out called "The Irish Soldiers of Mexico" which covers it in great detail.
The only thing with stepping him up against good quality - is that he might have to slug out a few wins like that against Cotto, I worry that Sauls fighting style might see him in too many wars and that by the time his prime comes around - he will have a declining resistance like that of Ricky Hatton. I like Saul Alvarez as a fighter, but I personally think it would be best of he went to a trainer like Floyd Snr, so that he could further increase his knowledge of a defence - because Saul already has the foundations for the shoulder roll, he tries to use it at times, often successful, but maybe needs a helping hand.
Fun fighter to watch and looks good for a 19 year old. But he did get rocked by a guy who jumped two divisions. He's a typical blood nut who loves some action but he will probably struggle against legit welters who can punch. Like to see him again though.