Walcott was a fine boxer, but he never was a great champ. He got jobbed in the first Louis fight, he won that fight no question, but he got KTFO in the rematch so he would have just lost the title there. Then he beat Ezzard Charles and got destroyed by Marciano in his defense. So Walcott, despite his skill, was the #1 in his weight class for about a year. Not exactly top 15 numbers.