Nunn is possibly the most overrated fighter of modern times. His entire rep is based around his first-round KO of Kalambay. He did nothing else of note. His mythical status is built around the perception of his ability, tainted only by his laziness. MTF
Nunn's rep is based more on the virtuoso performance against Tate than the Kalambay KO. It's easy to brush off that performance in hindsight, but at the time, Tate was an undefeated Olympic gold medalist who had looked impressive before hand and who was slightly favored over Nunn going in. Nunn made Tate look like he had never put on a pair of gloves before.
Nunn was THE MAN before the Kalambay fight. As Xplosive said, the Tate fight really showcased his abilities. He looked great against Toney too but got gradually broken down, down the stretch (took him too lightly IMO...I think he was a better fighter than Toney). Nunn beat Barkely, Roldan, Curry, Starling...he's not overrated.