So Carbajal moves up to flyweight and faces Danny Romero. Carbajal was a better fighter, but Romero was bigger and had a lot of power. It'd be a war, but I suspect in the end Carbajal being the much better of the two would overcome Romero's size advantage. Carbajal by stoppage in a violent fight.
Romero only had 6 fights at 112 or less; he was briefly NABF champion at that weight. At that point in time he was relatively inexperienced and, given that he had fought as high as 117 prior to those 6 fights, I'm guessing that making 112 wasn't all that easy for him. If his 7th fight at 112 was against Carbajal, Michael has a pretty good chance to win the fight.