You are saying they were at the very least as good and I'll explain why. You said Tua knocked out world title level opponents. So did Marciano but it took longer in fact they were world titlists current and former. That is to say that they are at least on the skill level that Marciano's two best opponents were on that he knocked out. But why bring them up if they weren't better? Therefore you had the intention that they were better. I don't want to argue over that little fact. If you honestly didn't then you honestly didn't. Who cares. But! Do you think Marciano's best opponents that he beat were better than Tua's best opponents that he beat?
If Moorer was a world title level fighter when Tua knocked him out than Joe Louis might have been an all time great when Marciano knocked him out.
I think that Charles and Walcott are better than any of the men Tua beat. I think that Tua's unprecedented early stoppages of Ruiz & Rahman (and other men) suggest that he had greater punching power than Marciano though, who had pop but was really more of an attrition fighter, imo. Separating a fresh fighter from his senses is very different than knocking out a tired, beaten man later in a fight.
Completely different principle. It was a lot bigger size jump in Tua's time. In Marciano's it was literally a 5-10 lb difference and common for Light heavies to venture up and fight heavyweights.
It could be seen like that. They had a different kind of power perhaps. But I was watching an interview with Bert Sugar where he was talking about Marciano's power and the famous picture of Walcott's face all construed from Marciano's punch. He said that was just one of the many Marciano punches and not the knockout punch like most commonly think. Imo I think he had great power but also wore down his opponents as well because he threw only power punches. Like Lastarza said, he would throw a hard punch and Marciano would throw a hard punch but the difference was Marciano would throw 10 more. Marciano had 10 1st round knockouts out of 43. The difference between Marciano's and Tua's opponents is Marciano's were far more well rounded and had much better defense.
Moore was nearly 40 years old! If you want to pretend you can be in your prime as a boxer at that age, good luck! Walcott was 37 for the rematch and retired immediately after. It's called revisionism.
Moore wasn't in his prime, he only appeared to be prime because he was doing the best fighting of his career. Like Marciano. Moore was also "nearly" 37, he could also be described as being in late 30s. Marciano could also be described as nearly 34, mid 30s. Both could be described as possibly past physical prime. They could also both be described as 188 pounds. One can be called a former light heavy, the other can be described as a former near light heavy. What story are you telling?