Okay so first off I actually just want someone from riot to actually talk to us about the thought process behind champion balance because it honestly doesn't make sense to me how they go about it.
For example, Sylas got gutted in patch 9.7. Like completely gutted to a point where anyone who isn't a pro just can't play them consistently since there are just so many better picks. He went from a 51% win rate to a staggering 45-46% win rate. He has since been left without any reconciliation buff. I understand that he was incredibly strong but anyone could see from the moment those patch notes went out that those nerfs would make the champion unplayable. And if all of the community saw it I'm sure that Riot saw it coming too. So why did they gut him so hard? They did the exact same thing with rework Akali (albeit rework Akali was horribly designed from the get-go with her true stealth. When everyone in the community knows immediately after seeing her gameplay reveal that she will be hell to balance I'm astonished that she got through development completely with that move in her kit.)
In complete contrast to Sylas, Jinx has been sitting at the highest win rate adc for over 5 patches now. Sitting at a solid 53% win rate and is undoubtedly a really reliable pick in any matchup. The same goes for Vayne, while she has not been at as high of a win rate as Jinx that is only because she is much more harder to play effectively but if you know how to play her she's clearly the best adc in the game. Both of these champions have been sitting as the best of the best in the bot lane for over 5 patches with not a single nerf to either of them while Sylas gets gutted and hasn't been brought back up to speed at all.
Another example is Morgana, with her recent update and buff to her W and R she has been one of the best midlaners in the game (while Sylas was still strong) and has yet to be properly dealt with and has been sitting at a 53% win rate in the mid lane for 4 patches.
How does Riot go about balancing champions? It really feels like a personal bias. The thing that tipped it over the edge to make me believe this was the Urgot rework and when he was gutted. He was one of the best champions in the game and was gutted with nerfs at one point and went to an abysmal 43% win rate. It only took Riot two patches to give him major buffs and make him really strong again and then toned him to make him balanced. Why on earth can the same not be said about countless other champions in the game currently who have been gutted and left with no buff? Rakan has been really feeling the nerfs to him as of late and clearly could do with a buff but yet Riot refuses to give him one.