I think he had an extreme killer instict, but I wouldn't say he's a psychopath. I think he's a very complex and misunderstood person. I bet if you got to know him he's a sweetheart.
I think during his prime he was almost 100% boxer. He was trained and disciplined very well. That number shot down eventually, though
'85-'88 Tyson was a closely monitored, carefully developed, computer programmed cyborg killing machine. He was the ideal combination of Dempsey and Patterson. He was also an exceptionally fast starter, very elusive and packed dynamite in both hands... Unbeatable in my mind.
With that said, his unbeatable prime was very short(in relative terms) as he quickly lost his discipline(while training and while in the ring) once Rooney was fired. He basically went from a bigger, stronger Dempsey/Patterson hybrid to a headhunter...sad:-(.