Pyke is not a support.

This is like a repeat of the mordekaiser rework failure. Just because you call an AP juggernaut an ADC doesn't mean he can actually fulfill the role of an ADC for a team. You're missing the entire reason why teams have an ADC in the first place. It's not just some arbitrary duo role you can shove anything into just because they do well in a paired setting. Fundamentally you need something that scales their damage well with auto attacks to have unmatched late game damage that can be delivered safely from range. Mordekaiser's rework doesn't fulfill that fundamental need teams have, so there's no reason to take him bottom lane despite having a kit purposely designed to do so. Nor is there really any need for a support when he's not that vulnerable in a solo situation. And the late game payoff isn't there to justify devoting the team resources to it.

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Pyke, likewise, doesn't fulfill enough of the fundamental functions of a support to be good at this role and truly called a support.

Supports do some or all of the following to a high degree:

1. Protect the ADC during laning phase.
2. Set up kills for ADC during laning phase.
3. Peel for and/or protect their team in teamfights
4. Set up kills for the team in teamfights.
5. Are force multipliers for their entire team. (ie. their abilities, when used properly, make a team much stronger than the sum of it's parts).

Pyke only does #2 and #4 to an extent, but doesn't even do it better than other options available. Although the ability to cause an enemy to be out of position is why he is labeled a "controller", subclass "catcher", and not an "assassin" (assassins don't have any abilities like this), the fact is that his passive and three other abilities do nothing at all to facilitate the controller or catcher playstyle. He's designed as an assassin first and foremost with a minor controller element thrown in.

Because of this, pyke cannot optimally or even really effectively fulfill the role of support for the reasons you actually need a support on your team. He will likely only have success in scenarios where you could have taken any other assassin to the support lane - ie. You get some early picks and get your lane fed. I mean, I can do that with Talon - but that doesn't make him a real support. Talon might fulfill the minor role of helping peel for the ADC in lane phase, but the real victory condition here is an assassin victory condition - kill lane, get fed, roam. About the only thing Pyke has going for him mid/late game is that he can CC more than Talon in teamfight contexts.

Pyke would have an assassin victory condition if he had more damage himself. But he depends early more on his teammates for damage. That's why many are saying he belongs in the jungle. There his minor catcher abilities combined with his roam abilities will be better put to use, letting a stronger support be the support. But it's typical for a jungler to rely on their teammate laners to help them secure kills so his lack of damage doesn't become a liability as long as he can CC and hook the enemy for his teammate during a gank. The problem with Pyke is that he was probably designed purposely to have bad clears as a way of arbitrarily forcing him into the support role. The only way he'll stay support is if his clears and early dueling are so bad that he just can't hack it in the jungle. Because he just doesn't belong in the support role unless he has no other options left. His lack of early DPS will give him no viable way of playing anywhere but support, but he will be inferior to most other picks in that role. So pyke will really only be played support by people who just want to play pyke, but have nowhere else to put him - it will have little to do with him actually being a good support.