Honestly I think Robert Garcia said it best about Chino: "maybe there was something that made him feel weak, so he could no longer believe in himself. Plus he can't come back, because he needs to lose 40 lbs and then what? Hell have to lose another 40 lbs". But he stresses "hitting the mitts hitting the pads is good for el chinos circulation, good for his weight." Also Andre Ward wanted to retire after the first Kovalev fight. I believe he was coaxed to keep fighting from his pastor. People thought he left the game early but to tell you the truth he was doing it all his life. Imagine what would have never been if he had not fought Kovalev the second time! Says Andre: "I'm tired."
Sorry for straying from the topic, Jones= after John Ruiz. Holyfield: after the John Ruiz trilogy, but there is some catharsis there: Roy came back around again and had a draw with iron Mike, somebody who he could've rode off into the sunset after the Ruiz fight with aka one last fight against iron Mike when they were about what? 20 years younger? And as for Holyfield, he got his wish, to fight till he could fight no more. Vitor broke a very old version of him in half, in less than one round. No it's ands or buts, retirement time. Maybe had he gotten the decision in the valuev fight he coulda had a nice retirement after what? 5 time champion of the world? And then with Ali, it sends shivers down my spine when he entered the ring I can't remember against who but he was already showing symptoms of Parkinson's. The problem is with every great fighter there is always one great fight left in them. Nobody wanted to fight paz, just like in MMA noone wanted to fight shamrock. For they would feel too bad if they injured them again. Sad stuff.
Ali after Norton III Duran after Barkley Tyson after Lewis Pacquiao after Thurman Holmes after Spinks II I give major props to Lewis and Ward for retiring on top and staying retired.
Muhammad Ali after Frazier III. Confident that his long term health would have benefited and his legacy would have been just as great. Only difference being that he would have been two time champ instead of three,but this would n't have meant that much in the great scheme of things. Duran after Barkley Tyson after Holyfield Pacquiao after Mayweather Holmes after Spinks II
Always felt like if Ali retired after Spinks 2 it would be the most movie ending career in boxing history. Being held by his team, waving his hand to the crowd, retiring as the first 3x heavyweight champion.
I think it should be before you get flatlined and when you have enough money to retire. Danny Garcia is a fine example. He no doubt has North of $10-15 million, has never had his clock cleaned, fought mostly the best guys, won't win a belt again but is hovering on Gatekeeper status.
Taking your criteria into consideration: Muhammad Ali - Should have retired after the Shavers fight. It was a very good win on paper, and nothing that he does after that, enhanced his legacy. It is not worth losing to Spinks, to win the title back from him. From a humanitarian standpoint of course, I would have liked him to retire earlier. Sugar Ray Robinson - This is a tricky one, and you could argue it a number of different ways. Personally I think that he should have cashed in his chips, after he won the title back from Basilio. I think that events after that, start to harm his resume more than they enhance it. Mike Tyson - You could literally argue this as anything from just before the Douglas fight, to just after the Lewis fight. Personally I think that the sweet spot would be after the Bruce Seldon fight. I think that his resume can manage without any wins he achieved after that, and it can certainly manage without the losses. Evander Holyfield - Again you can argue it a number of different ways, but I think that after the second Lewis fight is as good as it gets. Yes he lost the fight, but he was very competitive against the heir to his throne. After that the negatives far outweigh he positives. Joe Louis - He pretty much had it perfect when her retired after the second Walcott fight. There is but one wildcard in this. Maybe, just maybe, he still had enough left to get past Charles after he stopped Walcott. Such a win would of course have appreciated in value enormously. Ezzard Charles - I think that the two fights with Marciano enhanced his resume, so that would be a decent place to put a pin in it. However in his next fight he beat Charley Norkus, who was a good contender on a bit of a wining streak. Why not take it if you know it is in the bag, and have a decent win to go out on? Archie Moore - Only very minor improvements are possible to be honest. Having said that, the draw against Pastrano, before he fought Ali, is probably the best that he could have managed. Roy Jones Jr - Having been a boxing fan at the time, I know exactly when he should have got out. Right after he beat John Ruiz. People thought he walked on water after that!
Juan Manuel Marquez retiring after KOing Pacquiao would have been the perfect way to end his career. Erik Morales retiring after the Maidana fight would also have been a perfect way to go out.