i think they watched the lee fight and they think "when lee can mount him so hard, what will khabib able to do?"
if the first round would go 15 seconds longer, lee was winning that fight. ferguson looked very helpless at the end of the first round. the bell saved him, he was nearly finnished on his back.
a reason is i think why khabib gets so good odds lately because they see him with constant performance in the cage over all rounds. they know he can fight and grind over rounds. khabib is not the guy that ko`s people in the first round and lets room to speculate what he is able to do when it goes to later rounds (like ngannou, özdemir and so on).