Tito had decent technique but his approach was one dimensional. It was glaringly exposed as he moved up in weight. Just an example of how supreme size and strength can cover up a pretty big technical flaw. Footwork would fall under technique
Foreman appeared to have enormous natural strength he seemed clumsy but when he hit you he hurt even if some of his punches looked like arm punches he was exposed by Ali and Young both though were clever fighters.
When I saw the heading 'Foreman's X factor' I was dreading that somebody had posted a dream fight between George and Simon Cowell Foreman had great natural strength and phenomenal power. He also had great ability in cutting the ring off on opponents. Muhammad Ali said that George did it better than anyone he'd ever fought. George would have beaten a lot of guys who were more technically skilled than him. I would place him fourth or fifth in my all time great heavyweight list.
One thing about Foreman was he had a very good jab, underrated sometimes. He used it alot more in his second career but his jab was excellent when he was young also, when he used it. Look at his win over Chuvalo and see how well his jab worked early on.
Why do you need an X-factor to be great? If your one dimension works extraordinarily well, is that necessarily insufficient?
A factor that hasn't been mentioned, and something he didn't use against Young, was his ability to cut off the ring. Made it easy for him to get opponents within his reach, in which case proper punching technique wasn't even necessary most of the time due to his tremendous physical presence and power.
I wouldn't say George Foreman had chin sturdiness of the "very, very highest level" in his prime. Whether Ali or Lyle, it only took a few hard shots from a big man to either stagger him or floor him cleanly. Likewise for his having "terrible technique". His stance, guard and footwork are proper, and his jab and uppercuts with both hands are technically excellent. His left hook is thrown with due weight behind it. And his accuracy on the attack could be impressive: watch how he crushes Frazier for a second knockdown in Jamaica; his finding of Norton for the beginning of the end in Caracas; and his two demolitions of Frazier in the rematch. Personally, I'd say Foreman's X-factor was his unique, precious POWER. It was a gift. Off the charts and scales. As a puncher, he was a seismosaurus of the ring, and had the aggressiveness to deploy. In fact, this last quality crossed the line into lack of restraint with George, and, in my view, was the reason for his Achilles-heel factor: lack of stamina. But Foreman's X-factor was so large that quite possibly only a handful of fighters ever could survive to exploit his Achilles factor.