Chris Byrd was essentially a middleweight/light heavy fighting at Heavy all his career. I think both are similar in they are highly defensive guys, who had power although didn't always need to use it due to their superb speed and slickness. I think this would have been a solid matchup, although I think it could have had the potential for being a boring tactical counter punching fight.
But anyway Roy UD in a fight so exciting that around round 9 you would see most people leaving the arena because they couldn't contain their excitement.
Byrd just too strong for RJJ, unable to shake off Byrd, Byrd traps him into the corner and hammers away to the body. Late in the fight RJJ is too beat up and eventually gets stopped in the 11th.