Had Tyson retired in 1988 after the Spinks fight ...

[Endurance]

... he would have been remembered as the best fighter ever.
Don't really know where the myth Mike always quit when it got tough is actually coming from. A prime Tyson never quit and never would have - a complete fighter with speed, quickness, power, determination, style, heart, everything. The youngest heavyweight champ of all times, unified champion - just a great boxer, the best ever!

[JuicyJuice]

He literally stopped training after the Spinks fight and couldn't give a toss about boxing anymore (and he had nothing left to prove anyway), infact he was suicidal with the problems in his personal life.

He was a shadow of his former self against Frank Bruno and Carl Williams, and was getting beaten up by sparring partners in Tokyo.