I post regularly on a political forum where one of the most respected female posters is a Kansas grad who went to school with John Riggins. She has reported frequently that Riggins is very lucky he ever played pro football at all. Supposedly he harrassed and assaulted several females at KU, including a good friend of hers, but the university and football program covered it up and kept him out of serious trouble. She said he was easily the biggest ******* she met in college.
That being said, Riggins was an incredible talent especially in his early years. He would take a swing pass and either batter or outrun one defender after another, arrogantly holding the ball in one hand away from his body. I think fans probably remember him from the later years with the Redskins when he slowed considerably and was more of a Csonka type power back.