Poatan according to all international ranking systems (Fight Matrix, Sherdog, ESPN, etc.).
Who did Nemkov beat that makes you think he should be ranked higher?
All those rankings will always favor the UFC champion though. You didn't really mention why they ranked him higher.
Nemkov beat Davis, Bader, and Anderson.
Those guys pretty much left the UFC because they were boring fighters and needed to get paid in Bellator. Not because they weren't good enough.
For perspective, Phil Davis, Corey Anderson, and the late Rumble Johnson all beat Glover Teixeira when he was
in his prime.
Glover is a recent LHW champion, who toward the end of his career barely lost his belt to Jiri in an all out war. Jiri is Poaton's best win at 205 by a lot.
So this means that Bellator's best LHW's were definitely good enough to be champs in the UFC. Nemkov proved to be the best of all of them. He struggled against Anderson a lot in the first fight, but in the rematch he had improved to the point where he could beat him rather convincingly.
And if someone says Corey Anderson was bad, then no, he was boring and not marketed well. He was good, and for his age he was excellent. v People always forget fighters are not in their primes in their 20s in MMA, Corey left the UFC when he turned 30, so he was better in Bellator than in the UFC.
Someone like Phil Davis would have beaten many guys in 205, including Alex Peireira. He'd also beat the audience down by putting everyone to sleep.
Nemkov is not a 205er anymore, but when he was there he was the best for quite a few years. In before someone mentions he lost to Jiri at HW 10 years ago.