Not fighters like Buster Douglas who had one massive upset, but fighters who had consistent upsets throughout the course of their career. Fighters you could basically never count out, whether their upsets were small or large. Michael Sprott is a great mention here. Beat a 22-1 Timo Hoffman right after Hoffman went 12 with Vitali Klitschko, the only man to ever do so. Avenged two losses to Danny Williams with a point victory. Nearly outpointed unbeaten Vladimir Virchis. Upset 21-0 Cengiz Koc. And finally a few years ago nearly decapitated Audley Harrison and sparked him out. All this with a 31-14 record. Who else?
He is not a high level fighter, but Colin Wilson deserves a mention. He beat the highly touted at the time Rick Thornberry in his second fight. After losing his past three fights, he then upset the formerly world ranked and at the time highly touted Jimmy Thunder. After losing to both Bob Mirovic and Shane Cameron, he was an underdog again against Nathan Briggs, who was thought to be a reasonably promising up and comer, and he kod him twice in 5 rounds. After losing 5 out of his last 7 or 6 out of his last 8, including a last start loss to Nathan Briggs and looking old and gone, he drew with the Highly regarded Soloman Haumono. After following a KO loss to Alex Lapei who had previously been beaten by him, Wilson again looked down and out, but he rose to the occassion and scored the upset against John Hopoate. All in all, i think that while his standard is obviously limited, he scored more than his share of upsets.
Betulio Gonzalez came back with some big wins when many thought his career was winding down.NOtably the Espadas fight, when everyone was starting to look forward to the seemingly inevitable Canto vs espadas clash.
Mike Weaver spoiled some men's evenings for sure. He didn't upset Holmes, but he gave him all he could handle. As an older fighter he also gave Johnny Du Plooy his first loss, and also knocked out Carl Williams in a fight where he was expected to lose. Not a consistent upsetter, but a guy that won when he wasn't expected to sometimes.
Nate Campbell .Almazbek (Kid Diamond) Raiymkulov 20-0 .Juan Diaz 33-0 And lost razor thin decisions to Casamayor and Hlatshwayo. Was brought in as the ''opponet'' for both Diaz and Diamond, but upset the odds
The Jones/Hoppoate fight was sloppy, but VERY enjoyable. Those straight lefts that put Hoppoate down were nasty, especially the one that had him face down on the canvas nearly sparked out.