If you watch the video of Mike wrestling with his tiger it gives you a great insight into the mind of a fighter and how psychological it all is if you're doing it right.
There are three levels of brain:
The PFC which is the latest part and deals with higher order things like creativity, empathy, language (human)
The Limbic System which is in the middle and deal with autonomic processes, emotions, memory motivation (mammal)
The R Complex which is the oldest and deals with the basics like aggression, survival instinct, dominance (reptilian)
I think what made Mike such a dangerous fighter was that he could shift through these various modes of consciousness at will and was well accustomed to their traits/methods thanks to Cus who (by Mikes own words) broke him down and rebuilt him again and programmed him to become a god among men.
Everyone is programmed by life, their parents etc.. but its all haphazard. Cus did it with a single unified intent, to create the youngest heavyweight champ. And it worked.
Getting back to the tiger, thats how Mike could assert dominance over it where it would've just snapped on anyone else because he could shift into that frame which let it know who was the alpha and where it stood in respect and it played its position. Obviously if it catches him slipping or thinks it can get the upper hand then its all fangs on deck because thats nature.
Same thing with a fighter.
Mike himself said he was well versed in the art of skullduggery and how most of his opponents were beaten before he even stepped into the ring due to his mentality.
If you ever look into the psychology between species and how animal kingdoms actually work its fascinating how much is said without words.
except when it came to my boy Evander and the god Lennox Lewis