Think of some fighters who had great nicknames but were not as good as their in-ring moniker. Either because their nickname was just highly memorable while their fighting style wasn’t or because the nickname just didn’t fit them well. So that excludes the likes of obvious ATGs like the Sugar Rays, Hitman Hearns, Hands of Stone Duran, Marvelous Marvin (and yes I know he changed his name officially to Marvelous), or Iron Mike, etc.
DaVarryl "Touch of Sleep" Williamson, cracks me up every time. That said, he was a good puncher and KO'ed Corey Sanders. Still, funny nickname, eheh!
Jermain “Bad Intentions” Taylor Adrien “The Problem” Broner “Vicious” Victor Ortiz Devin “The Great” Alexander Cory “The Next Generation” Spinks Andre “The Matrix” Dirrell Kermit “The Killer” Cintron Chris “Nightmare” Arreola
To this day, Matt "The Predator" Vanda has probably a top 10 of all time nickname despite being sub par. In close second: Manual "Diamond Boy" Charr is a phenomenal nickname considering he has not had a sparkling career
James "Bone crusher" Smith. Awesome nickname for a guy who had power, but often utterly failed in actually using it effectively in the ring. Could put on pretty abysmal performances. Danny "Swift" Garcia...ironic because his feet are as slow as molasses. Pretty boring fighter in general who has many dubious decisions and lacks in both athleticism/high level skill.
Andrew "Six Heads" Lewis, i checked and he did not live up to his nickname . But he did once quit in a bout as he had a urgent need to defaecate.