It can be a turning point for better or for worse IYO. For example: Eddie Machen's loss Johansson: Prior to the Johansson fight, Machen was a more aggressive boxer-puncher w/ some explosive performances, such as this stoppage of Nino Valdes: This content is protected But after the shock loss to Johansson, he seemed to me to become more of a safety-1st defensive technician, doing just enough to stay competitive in big fights, but often failing to cut loose w/ the same intensity & killer instinct he had earlier in his career. Glen Johnson's win over Eric Harding: Prior to the breakout win over Harding, Johnson's trainer(s) persisted in trying to make him a boxer/sharpshooter, & he typically did just enough to fall short in big fights. For the Harding fight, Johnson teamed up w/ new trainer Orlando Cuellar, who overhauled his style to become the aggressive swarmer that we all know & love. That approach carried Johnson to an upset of the still highly rated Harding, followed by his biggest career wins over RJ & Tarver to become Ring's Ftr oty. Zarate's loss to Gomez. Prior to the Gomez defeat, Zarate simply walked down & overpowered every BW put in front of him. he tried the same approach vs. the naturally bigger & faster Gomez, but got a taste of humble pie & his career never recovered. In his next big fight vs. Pintor, he was uncharacteristically tentative, whether b/c the Gomez fight had left him gunshy or b/c he was making a self-conscious effort to box @ range more, & he ended up losing a controversial decision after a lackluster performance. Although Zarate retired ostensibly out of disgust for that decision, I think a general loss of hunger or confidence played a role as well.
Maybe... Duràn's loss to Hagler and Hearns. The Hagler fight..despite the fact he loses, he had gained more confidence now that he could hang with a middleweight,only to be humbled shortly by Hearns afterwards. But that Hearns fight..perhaps taught Duràn things about bigger fighters more,and he used that experience to get competitive with younger,bigger fighters later on.
Another two. Saad's defeat to Mustafa made him more aggressive,as his technician style wasn't convincing enough,he started to become a boxer-slugger to actually defeat his enemies convincingly. When Hagler drew to Vito,he wasn't satisfied and thus,started to try and ko people more n' more,cus he didn't like robberies.
Norton’s loss to Foreman imo, his confidence was never quite the same imo. Especially against punchers. He was able to remain calm against Foreman, execute his game plan reasonably well, and had an excellent first round save for the end. When he faced Cooney and Shavers, he seemed to have frozen, perhaps getting PTSD when tasting top-level power again. Though he was considerably past prime for both, and flat out shot against the former.
Ezzard Charles vs. Sam Baroudi Jack Johnson vs. Joe Choynski And career/legacy wise Larry Holmes vs. Ken Norton 15th round
Winky Wright vs Fernando Vargas …Wright completely changed his style from a cutie ….to an Ike Quartey/ Marlon Starling clone
Kevin Kelley's loss to Cobrita. prior to the Cobrita loss, Kelley was a more balanced boxer-fighter. After the beatdown by Cobrita, his chin was never the same & he was often reduced to being a dimestore Gatti, getting battered in fights before pulling them out w/ a miracle KO.
Another would be Saoul Mamby vs Sang Hyun Kim too,Mamby was originally just your average tough guy with some craftiness but crappy record overall,until he holds the title.
Tyson after the Holyfield fights. He was on his way to regain the undisputed title and secure a definitive top 5 place in history but those losses totally derailed his career.
Lloyd Honeyghan's brutal 2 round knockout of Johhny Bumphus. Bumphus had beaten Marlon Starling some months earlier and despite Lou Duva"s revisionist nonsense about Johhny being a walking zombie the fact Lloyd beat him with brawling rather than the smart boxing Honeyghan was known for was a fateful turning point. In the tv interview afterwards he stated ' I dont take any prisoners I dont come here to mess around'..in the KO magazine interview later in the year after his brawling shutout over Blocker and his 40 second destruction of Hatcher.....Honeyghan explained ' In the past I was wasting time boxing when I could get them out of there faster'. Some months later this neglect of his considerable boxing skills as well as his hard partying ever since he beat Curry caught up with him. Lloyd basically was never the same fighter during his world title days the speedy reflexes and slick defence and boxing that overcame Rosi,Shufford and Curry ( although he used some rough tactics there) . He went on to score one punch kayoes over Vaca abd Chung but he went on to suffer painful avoidable defeats to Starling and Breland. The odd thing is he carried on fighting for 6 years at domestic British and Commonwealth level and reverted back to tge fancy dan boxer...but now aged,without the reflexes and legs nor the punch power of his prime due to devastated hands.
The very 1st fight too pop in my head was this one. I saw it live. I thought Camacho would become a better fighter after it, because he passed his 1st gut-check fight. I was wrong, and Camacho went from the Macho Man to the Running Man , and would never win another fight when he was seriously pushed. So since you stole my Thunder. Let's take it back to Hagler vs Antefermo #1, A fight most thought Hagler won, but he got only a draw, and didn't take the championship. What was the result? " Destruct and Destroy " Was born. Hagler became a merciless pit bull. He went to the next level.....