Khabib is an elite wrestler with a solid chin. Two conditions I placed for a wrestler to defeat a boxer. The space issue is not about closing the gap but, wrestlers need open place to take their opponent down. McGregor, aside from the douchebag he is, defeated many wrestlers fairly easily. Eddy Alvarez is a wrestler, Jose Aldo is blackbelt in jiu-jitsu, Chad mendes high level wrestler( Chad beat him up in the first rounds).
Max Holloway fucked Brian Ortega up, high level grappler, to the point his corner gave up.
Besides you cant use UFC to justify street fights. How often did you see people going for a Kimura and shit in a street fight. f*ck that, we throw hands in the streets of eindhoven