Tucker had long-standing management issues, a disputed contract and bad finances etc. I think these issues contributed to him being sidelined after the Tyson fight, and he took the inactivity as an opportunity to get heavy into cocaine, which cause further inactivity. He was clearly past his best by 1991 when he fought this fight against Norris, but most of the top ranked fighters were in a similar condition.
When he was up-and-coming, he also missed about a year due to a knee injury.In the right frame, he should've been making his mark about late '82/early '83.
He was way more talented . When he lost it was always to much bigger men . When he won , it was also against bigger men. And he was rarely truly beaten.