Good examples....no, excellent examples...both turn of events would have been unlikely to have happened again.
I think the result of the Nunn--Kalambay fight qualifies. Now Nunn might very well win the bout, but ko1? over that guy? Dee collier ko1 over Cobb is a result not likely to happen. Or Earnie Shavers getting bombed out of there by a guy with 82 losses--Brian Yates. Lynn Ball ko2 Lyle was a big surprise and likely not duplicated. Tough to say for sure though, since everyone knew old Ron had slipped a few rungs down the ladder. But Ball was guy not even a blip on the screen. How about JC Chavez against Wise?
Willy Salazar stopping Danny Romero qualifies as a fluke I think. A young undefeated power punching world champ takes a keep busy fight against an oft beaten journeyman only to suffer a stoppage loss due to a fractured eye socket in a fight he was winning. Romero never quite lived up to expectations but he was too good to lose to the likes of Salazar without the flukey orbital bone injury I think.
Tom Bethea KO8 over world middleweight champ Nino Benvenuti. Who saw that one coming? Bethea was 9-5-1 and got a non-title against the champ and made the best of it. Nino set things right in the rematch, but Tom 'The Bomb' pulled it off the first time and managed the second go round for the title.
IN minor ways, Page losing to Berbick, and Dokes to Coetzee, if the being high on cocaine thing is true. Joe Manley beating Howard Davis Jr., and Rocky Lockridge kayoed by Juan LaPorte qualifies.
Larry Holmes getting his arm caught in the rope whilst throwing an uppercut at Tyson thus getting knocked out. I say he survives the round otherwise.
Holmes was on the way out regardless. He was taking a pounding and his legs were shaky. Nothing fluky about the 4th round ending.
John Tate getting caught in the last round after outclassing Mike Weaver for 14 1/2. Herol Graham after having Julian Jackson outboxed and cut over both eyes with a stoppage imminent gets cold-****ed in the 4th. This could also be referred to as pulling a Billy Conn. Ditto Ruben Olivares against Alexis Arguello.. All 3 of these are in the vein of a 'lucky punch'.