Well I would say the involvement of organized crime most noteably with Sonny Liston, Primo Carnera, and Ali-Terrell. Liston was a very strange case may have been involved with fixes, died mysteriously. Carnera was a pawn for the mob, there was even a movie made about him 'The Harder They Fall' (Humphrey Bogart's last movie). Terrell's manager tried to muscle Ali's camp into taking a dive, but "The Nation" (Nation of Islam) had Ali's back and took care of that manager...put him in a mental ward when it was all over if I remember correctly.