Tyson was and still is my favorite all time fighter to watch. I go back a few times per year and watch some of his matches. I boxed myself for many years so I truly appreciate the sport.
The thing about Tyson psychologically is he truly thought he could not lose. Ever and for him, that worked. He believed so intensely that nobody could damage him and he could reek havoc on anyone and he did, until Buster got the better of him on an off day. From there, the doubt crept into his mind and it lowered him down a few notches. It's like a kicker in football who makes 50 kicks in a row, misses one, then maybe a second and he's fucked up for good and is forced from the league and has to retire. You see it all the time. Nothing changed, but that slight mental edge. That is what happened to Tyson.
Tyson's punches were incredible fast, and quick, but landed with more force than any fighter in history. He was a true counter puncher first and before you knew it, he was on you and doing damage if one punch alone didn't end it. Watch his training videos, lightening speed and power behind those punches. Like a machine.
When he feared nobody, he was unbeatable, once he lost to Buster, he had doubts creep in and while it did not ruin him per say, it took him back a few notches.