League of Legends (LoL) Question: About Nocturne...

As per usual, it's simply a matter of shifting metas.

Nocturne hasn't been nerfed in a while. The last nerf that I remember him receiving was an increased cooldown on his ultimate, and that was S3. So it wasn't a direct change to his kit that made him unpopular, but rather changes to the environment he's had to deal with.

In solo queue, Nocturne has always been a good, albeit unpopular, pick. The global presence that Paranoia offers is immense, and can allow for map pressure even when lanes are heavily warded. The other aspect of Nocturne is the fact that he's a bruiser that heavily relies on basic attacks. Those have always been the key aspects of Nocturne, and that hasn't changed. What has changed is the need for these types of champions.

Strength in this game is determined by either raw numbers (think Lucian and Maokai) or meta (think Trundle). Nocturne has remained an uncommon pick for a while, but that's because the meta doesn't call for him right now. Remember when Feral Flare was released? Suddenly, Nocturne boomed into popularity because of how well he synergised with Feral Flare. What was a decent solo queue pick and subpar competitive pick became the most highly contested pick in both environments of the game. This was because, suddenly, a change in the raw numbers of an item heavily favoured him, and the jungle meta which centered around Feral Flare heavily favoured Nocturne, and he became a top pick. Same goes with release of Enchantment: Devourer. This item made basic attack oriented champions incredibly strong, and Nocturne was back in business again. And alas, this was nerfed, and Nocturne has returned back to the uncommon pick that he was previously in S4 and now S5.

At one point, while Lee Sin and Nocturne may potentially have had the same power level if the meta were not a factor, since the meta is a factor, Lee Sin may be more powerful than Nocturne because that's what the meta has become in League of Legends. The meta is about who's strongest. The strongest are the most dominant, and when the strongest get nerfed or the meta changes, the next best take their spot, and the strongest take another tier of champion's places.

To put it simply, Nocturne's power level has definitely changed. But it isn't due to direct changes to him, but rather direct changes to the environment around him. The game currently doesn't call for Nocturne because that's not what's 'in' right now. If suddenly, the meta shifted to global presence junglers, which it may actually be considering how some of the top picks right now are Rek'Sai and Pantheon (although in Rek'Sai's case, it's a matter of her being ridiculously overtuned).

TL;DR Nocturne is strong when the meta favours him.

I think part of the problem is that with the current jungle items, he's been forced from being a versatile champion in terms of what he can build into a very rigid one. You basically have to build Skirmisher's Sabre - Devourer and Blade of the Ruined King, usually followed by straight tank after that. When viable item options are limited, tiers become increasingly apparent, so anyone who can do the same thing better gets a lot more noticeable (ex. Warwick).