Communication of "criminals", ie. crime and athletes was more likely a consequence of the fact that athletes began to take part in the redistribution of spheres of influence.
Classic criminals - that is, "thieves in law", urki., on the contrary, were on the other side of the barricades from the athletes who worked "in lawlessness", did not recognize thieves' rules and authorities.
Nowadays radical Islamists are in such a position in the criminal world.
The intellectual level is about the same)
But seriously, in the 90s, many athletes, including the highest level, were out of work - there was no opportunity either to continue a sports career, or for coaching activities. Some went to crime: schematically, but quite clearly this is depicted, say, in the film "Beyond the Last Line" with Talkov and young Sidikhin.