Larry Holmes (20 defenses) from 1978-1985, and I select #13 Randall "Tex" Cobb.
Coming off the high of Cooney, the 20-2-0 Texan training out of Philadelphia was quite the "downgrade" in many peoples eyes. Even now in 2019 most people dismiss this fight as a complete washout.
However, in my view, this is peak Holmes. On this night I'm not sure 99.99% of the heavyweights of history could have touched him. So context is king.
Cobb was certainly no bum. He arguably was robbed against Ken Norton, whom Holmes won the title from. He had beaten Earnie Shavers, whom Holmes defeated twice. His majority decision loss to Michael Dokes was competitive as hell. Cobb also had wins over 19 others including Bernardo Mercado, whom Holmes defeated, and Jeff Schelburg.
Throw in his colorful past as a world-class kickboxer and his bombastic personality, combined with his remarkable chin, he certainly wasn't some easy mark. His rating was well deserved.
On a scale from 0 to 10 on the worthiness scale Cobb was about a 7 in my estimation. On a scale from 0 to 10 in terms of sheer dominance Holmes was a 9-and-a-half. Cobb wasn't as defenseless as Howard Cosell made him out to be. He had his moments, though few and far between. I don't give it a "10" because as wide as it was there wasn't any knock downs, nor was Cobb really ever in trouble of getting stopped (imho).
The problem with Cobb is that he was an arm puncher, so even the rounds he was decent or good in just didn't register (in my view) because he didn't punch with authority. That's basically what cost him the Norton fight (in my view) because Kenny hit harder and that made more of an impression on the judges.