You said he had "relatively weak chin" that for me is a baffling comment. I would say his chin is definitely above average based on Tyson fights alone, he took tremendous punishment in those fights. And I don't think he was ever quite the same after those fights. He had a broken jaw and broken ribs in the 2nd fight, and as @Contro said it's one of the rare fights where two big punchers are loading up with every shot, and getting hit consistently for 12 rounds in Heavyweight division.
I think it would be pretty competitive honestly. Ruddock wasn’t as good as people remember him as being. His performances were very inconsistent and he wasn’t the smartest guy in the ring to say the least.
I respect Andy more than most people do, and I think he COULD win this, but I too favor Ruddock with his physical advantages.
Unfortunately, Razor didn't beat anyone, he lost all the fights that meant he could go one step further.
If this is fantasy world, you could argue that Ruddock could box patiently behind a jab. More likely, he gets increasingly sloppy due to having a 265 pound tank pushing him around and gets tko'd in the later rounds. Ruiz at his best was vulnerable to top tier boxers, but was capable of taking out anyone who would trade with him. Ruddock belongs to the second category.
Nothing should be baffling. It is relatively weak compared to the "iron chin" that was claimed. Not hard to understand at all. Or maybe you just don't know what "relatively" means?