Kamaru Usman is in the midst of the worst stretch of his career -- at least as far as wins and losses go -- but the Nigerian Nightmare says don't get it twisted ... he's still the best 170 lb. fighter in the world's top MMA promotion!
The former longtime welterweight champ, now ranked 5th, joined Babcock on the "TMZ Sports" TV show (airs nightly on FS1) ... just days before his highly anticipated scrap with 7th-ranked Joaquin Buckley.
Kamaru says, despite a 600+ day layoff, he's ready to go.