He was sparring elite fighters and had already been in there with Shane Mosley. Before and after Mayweather he was still blasting people out. He wasn't green. He was schooled by a superior fighter who took everything away from him. Credit to Canelo though. He dedicated himself and become a much better fighter. Sometimes you have to go to school
Canelo turned pro at 15 or 16 and as others have said fought dozens of club fighters to get experience. Not all fighters age the same in terms of development or Iongevity. Canelo that fought Floyd had even worse stamina, couldn't fight coming forward (kind of needed versus Floyd), and really used an awful gameplan...who tries to outbox a smaller fighter??? The 168 Canelo would batter Floyd. Yes, Bivol boxed Canelo but Bivol is taller, longer, and has a bigger frame. Bivol can absorb those punches to the shoulder, arm, chest, and occasional clean flush lands without an issue. A 147 pounder, whether its Floyd or not, would not be able to absorb those punches. Dont believe me? Why did Floyd need 152 for a 154 fighter? No chance he fights a 168 fighter at 168. Just not happening. And that's no knock on Floyd but its ludicrous to think Floyd's an exception to the rules. Weight classes exist for a reason.
Shane was done, and he could barely beat Trout back then. So he was in experienced against elite level fighters.
The age when a professional boxer stops being "green" is individual and cannot be generalized. Certainly, a 33-year-old boxer has more experience (life experience in general) than a 23-year-old professional boxer (for example, Floyd MJ vs. Canelo). The arguments made by @steviebruno are valid. But the matter can be viewed in another way. Since today in the Top 10 heavyweights there is no one (or almost no one) under 30 years of age - a 23-year-old professional boxer is certainly "green". So I repeat: The age when a professional boxer stops being "green" is individual and cannot be generalized.
It entirely depends on the fighter. Like you said, Mike Tyson had already peaked peaked before the age of 23. But most fighters tend to be in their primes in their late twenties to early thirties. That's typically when there's the perfect balance between youth and physicality combined with experience and skill. But of course, there's always going to be plenty of exceptions to the rule. In Canelo's case, I feel like his prime was from the Chavez fight to Saunders fight. But that doesn't mean Mayweather's victory over a pre-prime Canelo isn't still a worthy scalp to have on his resume.
Canelo was the same age with more experience when he fought Floyd compared to Lopez when he fought Loma. I dont remember anyone calling Lopez "Green"
It's not a question of age but of background. When Canelo faced Mayweather he only had one world-class fight against Trout. His other six title fights were gifts from Sulaiman.
If you put the best version of Clenelo in with the best version of Floyd, Floyd takes a savage beating before getting knocked out. Floyd didn't fight the best version. You have zero case for arguing that Floyd did. PERIOD.
Not that green. But he's had a long career after Floyd and changed. That was a great win for Floyd for sure, even if a bit tainted due to catch weight. Canelo seemed fine though.
“Green” vs world level champs is one thing. “Green” vs elite level ATG fighters that is something completely different. so like others have said - it depends on the fighter & the individual scenarios.
Lennox Lewis and Wladimir Klitschko weren't at their best at 28 yet, so yes, you can be green at 23. Both of them were very good though already and so was 2013 version of Canelo - he just didn't reach his peak yet. Saying that, Canelo not only lost to much smaller 36 y.o. Floyd, he was thoroughly dominated.
So if he had beaten Floyd instead of losing 10-2, you wouldn't say that he was green. It's almost as if the result of the fight dictates whether or not he was green... ... Do you not see how this is circular reasoning?