Examples of very good heavyweights losing to opponents 30+lbs smaller?

It's hard to know since the rules in boxing generally prevent these kinds of match ups from occurring and getting sanctioned in the modern day. Almost all of the examples we have of little guys fighting big guys involve the little guys bulking up to a weight class by getting fat, not cutting weight, or weight lifting. But the extra weight always slows the littler guys down and they don't look as in shape as they do at their prime weight. The only modern examples not listed above where guys who weren't heavyweights fought against heavyweights were in exhibition type things De La Hoya vs Shaq or Buakaw Banchamek vs Hong Man Choi.

 

It would certainly be fascinating to see. SRR absolutely used to compete with much heavier men, rather good ones too. Guy rolled LaMotta giving away almost 16lbs which is a lot given the context of the match.

 

Well hell, don't we see someone beat a guy with a twenty pound weight advantage almost every week because of day before weigh ins and rehydration?

 

Shouldn't it be similar for both?