Nate wouldn't be in the top 50 for pro boxing. He may be a good boxer, by MMA standards, but not by pro boxing standards. I have trained at boxing gyms, I don't think he could win a golden gloves event, let alone hang with anyone in the pros.
Yes boxers have been proved to get destroyed in the cage, but the cold hard fact is, put a top mma guy in a ring to box....and just box, he gets smashed by a pro boxer.