I honestly don’t think the term applies to him. He had a stretch where he was fighting well in his later years but even then wasn’t consistent. His career was a rollercoaster with wins over some very good fighters at times and losses to some average or below ones.
I guess I just don't see any reason to treat Walcott as having not been in his prime in 1946, when he dropped the decisions to Ray and Maxim, but in his prime a few months later. Especially considering that the Maxim decision was highly controversial and the fight probably wouldn't even have been close had he not broken his hand in an early round. Walcott was already considered one of the top heavyweights in the world by the middle of 1946 when he lost the major upset to Maxim. I haven't read anything suggesting that he was an improved fighter when he fought Maxim again in 1947. (And he barely lost to Ray in 46 and barely beat him in 47. Seems like he was pretty much the same fighter, as far as I can tell).
The Walcott who was knocked out by Abe Simon was prime. People hate to accept because they have formed such an inflated estimation of Walcott.
I believe the lae 1930s was significantly stonger than the late 1940s/early '50s, yes. Even with Joe Louis depleting the ranks with his busy schedule.
If you think that Waloctt was in his prime when Simon beat him, then it would not really be enough to say that the late 30s was "a significantly stronger era than the late 40s/early 50s." You would basically have to conclude that it was one of the strongest eras! The implication would be that a man who was the strongest contender of the late 40s/early 50s, and a world champion in of that period, could not beat the second raters of the late 30s!
It is absolutely enough. No. I'm making no comparison with "all other eras". That's completely unnecessary, over-complicating and irrelevant to the question. It's a fact, not an implication.
I suspect there's a little bit of room to move here with Walcott's results and ratings over the years.
He was 26 years old, officially anyway, and had been professional at least 9 years. It was the last fight he had before going into a 4-year retirement and coming back in his 30s. There's no reason to believe 4 years out of the ring and coming back in his 30s actually put him in or brought him towards a "prime".
I think Walcott's "greatness" lies more in the fact of his exceptional longevity, rather than him actually getting better as he got older. He was very well condititoned and stayed hungry for the big fights, so when he came back in 1944, with the talent of the division entering a lower phase (due to war disrupting the sport), and with a connected manager, he started to achieve success. Joe Louis wasn't as hungry and clearly underestimate what Walcott was capable of, and probably deserved to lose to Walcott. But KO'd him in the rematch. But Walcott kept going and eventually won the title on his 5th attempt., against all odds. He deserves to be remembered as a great inspirational fighter and a worthy champion but he wasn't some magical fighter who suddenly became loads better 15 years into his pro career as he reached 32 or 33 or whatever. I don't think so anyway.
Potentially Walcott should have been at his best before 1940 but during that first career Walcott missed a couple of years out. I don’t think he fought in 1932 or in 1934. He only fought once in 1931. It is a patchy record before the four year break from boxing. Even if he did score some good wins in the 1930s it seems he just was not being matched to his potential. Matchmaking is a bigger factor than people realise. Nobody ever looked prime without great matchmaking. You have to beat the right fighters in the right order to reach the next level. If you don’t get the right opponents in the right order you can’t beat them in the right order. Then you don’t reach that level. because they beat you. Muhammad Ali could have been 0-5 in his first five fights if he was matched bad enough. I do think the 1930s was a very strong era though.
As far as I can tell, Walcott was never really functioning as a full time fighter before the war. So while this should theoretically have been his prime, it was not the best version of him that ever existed. The Walcott of the first Louis fight, would probably have done better in his place. Essentially Walcott's prime never happened, and I don't think that Elmer Ray's did either. I also have to come back to the implications of your assessment being correct. If the best version of Walcott was losing to fighters like Abe Simon, Roy Lazer, and Tiger Jack Fox, then you would probably have to conclude that men like Lou Nova, and perhaps even Tony Galento, were significantly better than anybody around at the high point of Walcott's success. This arguably puts the era up with the 70s and 90s!
mrkoolkevin posted an article not too long ago where Walcott claimed he was in great shape and well prepared for Roy Lazer, for an example Lazer outpointed Walcott.
They were all about the same level. If Tony Galento had a 1947/'48 Joe Louis to deal with he has a very good chance of being world champion.