Mike Tyson had a great amount of boxing knowledge. He watched tons of tape. He didn't just "forget to move his head". He had just lost to douglas who jabbed his head off. So he knew what happened when he got lazy and didnt take his opponent seriously. he trained hard enough to be ripped to shreds vs Ruddock so why wouldnt he bother to try to be elusive against a big puncher like ruddock when even 10 years later when he was shot to **** he still tried to jab and move his head against Lennox Lewis and he did also in the Holyfield rematch in 97(with the same trainer he had vs Ruddock). Lewis and Holyfield used snappy jabs. So Tyson moved his head to try to slip them. Ruddock just stuck his left hand out and aimed a power punch to whatever side of his stretched out left hand Tyson's head bobbed so Tyson came straight in and fired a straight right when Ruddock exposed his chin by loading up the smash. More specifically if Tyson slipped the outstretched ruddock left to the outside ruddock fired the hook, if he slipped it to the inside like he did vs Carl Williams then ruddock fired an uppercut. If Tyson's head stayed in place he threw a straight right. Tysons decline had to do with a lack of dedication and desire. Showing up out of shape, loading up big shots without defense and a lack of combination punching is a symptom of lazyness and wanting instant gratification(post prison if his opponent put up a fight he would start misbehaving) moving your head takes energy and concentration to keep doing he knew he had to do it to survive vs Holyfield(rematch), Lewis, golota and even in the exhibition he did after he retired he moved his head. Ruddock was trying to set him up by holding out his left and baiting Tyson to weave or crouch into a bomb. Simple as that. Had ruddock boxed and snapped jabs out then Tyson, having a good boxing IQ, would have started moving his head.
I think a lot of Tyson's strategy was to avoid The Smash. Tucker nailed him with a left uppercut in round 1 desoite Tyson being at his peak.
Mike's decline was Mike himself It took so much discipline to fight bigger guys and not get hit, so he needed his bobbing and weaving style to be so exact and sharp. And it was. But once he started to focus on things outside of boxing his defense started to slip and he was getting hit more and more. By 1990 he lost. Then it became a guy who was a great puncher who could get by with it for the most part, until he fought someone great also..
His reflexes were not the same as his early days. That's what losing by ko can do to a guy. They don't lose all their reflexes but they sure lose some of them. It's a step down the ladder and the question becomes how effective they can remain 1 or 2 steps below their peak.
I remember E.Steward saying yrs. Before Tyson started his decline his(Tysons) style of fighting wouldn't be sustainable as he (Tyson) got older. So was it lack of discipline or the natural effects of getting older, and fighting the frenetic style he fought earlier in his career wasn't possible anymore?