Khabib has an elite array of weapons compared to Lee in teh takedown and teh clinch. It's very visible in the takedowns that both of them use. Khabib in the octocage, has been seen using not only single/double leg takedowns, but also Judo throws and sweeps which he implemented inside his grappling game. As for Lee, its all wrestling based takedowns which are his bread and butter. Not to mention Khabib is not only skilled in wrestling, but also in judo and a world sambo champ, plus he was a NAGA no gi grappling welterweight champ.
Also, I've never seen Khabib fighting on the back foot. He's always the one piling on the pressure. This certainly supports in getting the takedown. But as for Lee, we've seen how he fights when he's put on the backfoot in the fight with Raging Al. He doesn't fare good there seeing how he lost that fight.
Overall, I think Khabib would wreck Kevin if they grapple. Thoughts?