If Roy had eaten a few more steaks and kept training with Mackey Shililstone for another year he could have take on Ronnie Coleman for the Olympia. When Evan Fields needed to gain weight he just trained with Lee Haney, 7 time Mr Olympia, and bought a few supplements down at Balco.
Roy was one of the most athletically gifted fighters of all time, he was unreal at his peak, even watching him do punching drills in training was a thing of beauty. When his reflexes started to wane, that's when he started getting hit clean and ko'd. The reason Hopkins aged better and can still compete at elite level, is because he has a superior boxing IQ to that of Jones, who just couldn't adapt to losing a percent of his athletic gifts. Roy's style relied on him being phisycaly superior, once that went he wasn't the same at all.