Yes he was 36-0 with 29 wins over fighters without a profesional win. He beat Mitchell, McCaffrey and Herald who as a group never won a major fight again. Sullivan really should have lost his belt against Cardiff in the fight where he broke his arm though that fight was ruled a "draw". Cardiff who was by far the best fighter Sullivan fought with gloves before Corbett also never won a major fight again and lost to Peter Jackson, Killen, McCauliffe and Godfrey. Sullivan then took 5 years off but got to keep his recognition as champion.