Close fight, but Yuri was more technically and fundamentally proficient, and better defensively IMO. I think he'd win the majority of rounds by sharpshooting the slower-footed Carbajal and controlling the distance. I thought Carbajal seemed to regress skill-wise as his career progressed, but if we take the best version of him, he'd make it a highly competitive fight. Arbachakov is my pick. 7-5/8-4ish.
Carbajal will be eating Arbachakov's jab and straight right all night. But Carbajal will have his moments.
Although I might favor Yuri by a razor thin decision, I would NEVER count out a prime Carbajal. Guy had serious guts, and serious power for that weight. If he had taken his career more seriously, he could have reigned far longer.
I would pick Yuri to round out a 8 to 4 decision, as has been stated previously, in an awesome skilled battle, but I honestly don't think a sudden KO or stoppage from Carbajal would be unlikely. Yuri, for his amazing textbook technical style, had a minimized movement, reflexive defense to go with it. It usually worked most of the time, but I wouldn't say his reactions were 'extraordinary', not in a way to make a KO punch from Carbajal seem trivial, especially later on. Yuri was also another boxer, like Canizales, who was amazingly skilled but could box within himself (his under usage of his left hook is an example). Carbajal's crazy power could make Yuri a bit gun shy later on.
Got to say, I'm enjoying seeing the little guys getting a run out in these hypotheticals. All depends on how Arbachakov handles Carbajal's power, because although Yuri is the better technician and more technically sound here, he still got hit a little more than he should have done. But he was more tactically astute and cool-headed than Chiquita, so while Carbajal would likely have him in a couple of crisis moments, I could see Arbachakov finding a way through it. Think it'd be close, but I'd take Arbachakov by decision. Something like 7-5 in rounds. Would be a great fight to watch, because while Arbachakov was a fine boxer he was no runner and could handle himself when he going got tough.