Mike Tyson did enough to warrant a Top 10 All-Time Heavyweight ranking:

-Youngest guy in history to win a version of the World Heavyweight Title.
-Unified all 3 Titles.
-Destroyed an undefeated Michael Spinks for the mythical Man-Who-Beat-The-Man designation.
-Was rated Pound-for-Pound #1 in 1989, (Julio Cesar Chavez #2, Whitaker #3, Nunn #4, Meldrick Taylor #6, Azumah Nelson #7.)
-Was a dominant Heavyweight Champion for a few years in a worldwide talent field of over 1 thousand licensed professional Heavyweight Boxers.

His achievements merit a Top 10 All-Time Ranking. Other men are there with less. I don't think Tyson warrants a Top 5 though.
He didn't have longevity. When the going got tough in a deep fight, he didn't show that Champion's ability to turn the fight around to achieve victory; he got frustrated and went to pieces instead.

In his prime, circa 1986 to 1988, Mike Tyson was absolutely phenomenal...