Agree with this, but my thesis is that even without the ulcer or the concussion, his age was going to stop him.
You know the game slaps? I used to be deadly at slaps. My hands were never especially fast even among amateur heavyweight boxers or even my own gym, but I did train on and off for a total of about 15 years, plus I can juggle, which made my hands faster and reflexes sharper than like 95% of the population. Even in my early 40's I could bust basically anybody's ass at Slaps. I could even close my eyes after a couple of minutes and beat them because I'd have their movement pattern in my head. Last year, at 50, one of my kid's friends heard me talking about slaps and wanted to play, and this kid just beat the shit out of my hands. I saw what he was doing and I knew what he was going to do before he did, but it just didn't matter because I wasn't fast enough anymore.
All those videos where Tyson can clearly sees the punch coming and doesn't even attempt to slip, or just stares as Paul presents his chin are nothing more than an old man who has run out of gas.