Saad would be too much for Carlos to handle.This is Matthew's fight to lose, he could end it anywhere from the fourth to the ninth round.
It would be like the first Yaqui Lopez fight, as Saad would outjab Monzon. Monzon has little to trouble Miracle Matthew with IMO, though his ring I.Q and ability to set the range would probably see him survive the distance. He'd get his jab off, but he lacks the size here and, despite possessing a heavy clout, it's hard to imagine him carrying that up to 175 against a big Light Heavyweight with the propensity to take pain like no other. Saad decision, or if Monzon really brings the fire after losing the battle he wants to win, Saad will take him out. It's hard to imagine Monzon unable to do his thing and whipping out something completely different, but he's in with too big, hard, skilled and powerful a man for me to give him much shot here.
If you use Bennie Briscoe as a connection between Carlos and Matthew,,,,,,, Then I'm going with Monzon by a close decision.
How does a Monzon who never fought a light-heavy move up and beat one of the toughest and most deadly around? A man against whom he has no physical advantages, unlike when he was at 160? Saad by KO late. Monzon had good middleweight power, not great at all, and Saad had great 175 power. Plus took a great 175-lb punch. Monzon would have to prove himself against SOMEBODY at 175 before being given a chance in this fight. Same if it was Hagler moving up to fight Saad.