Matthyse would kill him. Maidana would kill him. He is 'banger' who gets banged by real bangers and gets outboxed by any decent fighter
No question, Matthyse, he is a much more skilled brawler. His defense is actually pretty good, and his punches are even better. Rios is a dip**** anyways.
This would actually be a really even fight IMO. People may underrate Rios's abilities now because of his sub-par performance against Abril, but Matthysse is no Abril, and at 140, Rios would be a lot healthier and would be able to fight in a more physical fashion. Stylistically, whoever makes the other back down first would probably gain enough of an advantage to turn the fight in their favor, since neither has shown the ability to fight going backwards. Matthysse's reach isn't too long, but he does need some space to punch and is awkward on the inside. Rios is quite comfortable there, and assuming he can close the distance as well as he did against the likes of Acosta, then I think he can use short punches to wear Matthyse down. There's always a chance his lackluster head movement sees him run into a hard right hand that backs him off and allows Matthysse to assault him, but Rios also has a good chin himself; the early rounds would go back and forth in such a way, and I can see either taking it once they jump on the opportunity to back their man up and keep throwing at their preferred range. I don't think this fight would go the distance.
Matthysse is a decent boxer with decent abilities and a monster puncher. Exactly what Rios doesn't need. Rios will do better against soto,Alvarado.
Matthysse would murder Rios, but the fight would never happen, because Matthysse is Golden Boy, and Rios is Top Rank.