Rahman would knock out Deontay in 2 rounds. Even Kownacki would be a favourite at this point against Deontay and he is barely top 20 in this weak era, after he bounced around and stopped in 4, the football soccer holigan, who were told was in Wilders top 3 best wins Come on.
Rahman is an ATG legend compared to Wilder. Inside the first 6 years of his career he fought Maskaev, Tua, Sanders and Lewis. Wilder is still in Bumsville almost a decade into his career.
Rahman stops Wilder, he potentially could put a beating on him. He had a good jab, good power and was physically strong. Rahman's issue was that he was fairly slow. He gets flack for his chin but Rahman has to be the most durable chinny guy ever. I've seen Rahman both shrug off bombs to win and seen him hurt by things he shouldn't have been hurt by. At his absolute best, he outboxes and ko's Wilder.
If we are talkin' a priime version of Hasim The Rock Rahman, he would handle Wilder with ease just another day at the KO office .... Dude was a beast. A strange chin, as agreed with others he would take some serious shots and return with his own. He is usually durable as hell and even a totally dehydrated and absolute shell of a fighter he was, Rock withstood the onslaught of Alexander Povetkin. Yes he was atrocious but he was stopped on his feet. Rahman's physical abilty would make things complex for Donky. He had the best jab in heavyweight for years but his slow plodding was unneeded, If motivated though and he came t fight it'd be over by 4-5 rounds for the Rahman by KO win. Making him 3rd time champeen!
Rahman was KO'd 3 times in his prime. Maskaev, Tua, and Lewis. Logic to me says that a taller, rangier, just as (or almost as)hard hitting heavyweight as those mentioned could take him down, so could Wilder. On the flip side, Wilder has never faced anyone close to Rahman, resume wise. If Rahman could weather the windmills like he weathered Sanders, then - bye bye Wilder.
Both have Glass Jaws with big punches, but The Rock has been in there with vastly superior fighters than The Windmill. Could legit end up in a double KO, but would have to favour Rahman.
A favorite ploy for boxing fans, including announcer fans, seems to be tagging their fighter as being way past prime when he loses. Strangely, the opponent is never the better man or the better fighter. A poignant example of this ploy in the works is the highly anticipated Canelo Alvarez vs Golovkin fight. Already one can see the past-prime-excuse being cunningly prepared for a Golovkin loss. I imagine that if Ortiz, aka The Real King Kong, loses to any HW, his fans will immediately avail themselves of the same excuse by claiming that it wasn't The Real King Kong that lost but The Real King Cong wayyyy past his prime that was soundly defeated.