According to TLC maybe. :: He was highly ranked but I don't think he was ever #1 . Wasn't BJ Penn tearing up the LW's at that time?
Most people argued either Aoki or BJ was the top lightweight back then, with the difference between the two being, most of the best 155ers at the time were fighting in Japan, and the UFC's lightweight division was pretty much Penn, Sean Sherk and nothing else. TFK
Besides Aoki, and as you mentioned, Hanson? Gomi, Kawajiri, Alvarez, JZ, Ishida, Ribiero.... I'm sure there's others I'm missing. Even Melendez was starting to make a name for himself in Japan. TFK
Yeah, my comment about fighting Hellboy and Aoki is with the benefit of hindsight. Following the first Dream 155 lbs Tournament, most of the guys considered in the Top 10 at 155 were fighting in Dream. The obvious exceptions were Penn, Sherk and Josh Thompson. Funny but following the Dream tourney, and before Aoki beat Alvarez, Sherdog had Alvarez, Hellboy, Gomi, Aoki, and JC as the 2,3,4,5 and 6 fighters in the world. Penn was in the top spot. Penn and Sherk were the only UFC Lightweights in the Top 10. And Josh Thompson and Melendez were already in Strikeforce and regarded as the 7th and 8th best.