Those rankings were not when Khabib fought them as you probably know
Ed Barboza was the only top ten fighter
at the time of the fight which Khabib has beaten by decision as almost always usual. A fighters ability can improve with experience, coach, conditioning etc
Michael Johnson - Prelim card on UFC 205 won by submission in round 3 while Conor ko'd reigning champion Eddie Alvarez in round 2
RDA - Prelim card won by decision on UFC on Fox: Werdum v Browne
Healey - bottom fight on main card UFC 165 again won by decision