First one comes to mind is Castillo -FMJ 1. If Castillo gets the decision Floyd and his fans would no longer be able to say no one could ever beat him Hagler- Antofurmo 1. If Hagler gets the decision we could be talking about Hagler with the most middleweight defenses instead of Monzon
Robinson-Castellani - Robinson's SD win earned him a shot @ Bobo Olson's MW title, which he won surprisinglly easily, & the rest is history. Who knows what would've come of Robinson's comeback efforts or career as a whole if he doesn't get that decision?
If men like Witherspoon or Williams got decisions over Holmes, it would've shaken up the 80's title scene a lot. We might've gotten a unified champ other than Tyson way earlier if Tim got the win over Larry- Either he, Thomas, or Berbick would've likely become undisputed far before Mike. I personally believe that Holmes rightfully got the decision in each of those fights, but who knows what could've happened.
If Jimmy Young had been given the decision over Muhammad Ali,then Muhammad would have been the first three time title holder two years earlier than he actually was. There would have been a rematch by September '76 with Ken Norton and Richard Dunn being paid a handsome amount of step aside money. Ali would have made sure that Young would n't have beaten him again by training hard. If Norton had given the decision in his Yankee Stadium bout fight with Muhammad then I can't see Muhammad winning the crown back. Ken had Muhammad's number after '76 as Ali was too shopworn by then.Muhammad had enough left to beat Young but not Norton. If Marvin Hagler had been given the nod over Sugar Ray Leonard then retired it would have done his legacy good but a lot would have sympathised with Ray over it.
Golovkin getting the nod over Canelo in one or both fights could have taken things in a very different direction.
Doesn't every decision ever change history in some way? Butterfly effect and all that jazz... Who knows, maybe if a random Argentine journeyman never gets jobbed against a prospect in the 1920s, Muhammad Ali might have never been born.