Absurd. Toney is amongst the hardest boxers of all time to KO. Aside from a monster punch that caused a flash knockdown in the Reggie Johnson fight early in his career, he's only been knocked down on balance KDs (against Peter and Jones). He has that rare combination of a great chin and a great defence, which is found in very, very few boxers... ... One of which is Marvin Hagler, which was the inspiration for this thread!
I think this would be a close call, Toney's defense, countering and technical skills would give Hagler the same problems Duran gave him. This would be a technical thinking man's war of a fight, Toney's defense, straighter punching and countering offsets Hagler's attacks. I slightly favour Hagler's better workrate to edge out the decision here but he wouldn't look too impressive