Dunno about ever. That takes some thinkin. Buut right now, it's Serg. I seen his name poppin up in fantasy fights against ATG fighters at 154-160 n ****, and it's crazy. He havin a nice lil run right now and he a good fighter. But he ain't great or deservin of all the hype he gets.
Overrated fighters were/are those who built/build up their records and became/become champions or highly rated contenders at least, without fighting worthy, notable opponents. A guy who fits this profile perfectly is Saul Alvarez. An inactive example would be Arturo Gatti.
Recently it's been Bute and Khan. Both have had good careers and can turn around their recent low points, but the way they were being talked about was simply out of control...
Vitali Klitschko By far the most overrated fighter in history; overrated chin, overrated power, overrated ability & overrated career. The praise he gets is absurd.