I don't think either guy is a top HW. But to suggest that Nelson would handle Carwin easily is ridiculous. Both guys are extremely tough and durable, which would lead me to believe that this fight could have easily gone the distance....and if I had to give the edge to which guy would finish the fight I would pick Carwin by KO.
Now...back to the actual topic at hand - Mitrione. He's a great athlete and a really tough guy with a lot of potential, but he just looked terrible in the Kongo fight. I think Roy will be too tough and too experienced. I still expect a competitive fight though.