Castillo would have tuned him up. Rios had the size and strength to hang around but not the skill to out-fight Castillo, who was more varied, sharper, and more creative.
Perfectly said. Castillo in his prime was so good. Known for his toughness and strength, he was also very smart and skillful.
Castillo was more of a mid range kind of guy. He was at his best when he had a little bit of space. Too me he was a very methodical fighter that like to control the space and tempo. Rios was more of a classic pressure guy that liked be on the inside. To answer your question I would say Rios. Castillo certainly could fight on the inside but it wasn't his preferred range.