So, Riot had an issue with Yuumi wherein this champion they intended to be accessible and simple ended up being very exploitable in pro play, and having an actually high mastery curve so she wasn’t even usable by the intended audience.
They did what they did for a lot of pro tier problem champions in that they reworked her, removing much of her skill expression to bring low tier and high tier Yuumis closer together, and make her less dominant in elite tier without having her winrate being nearly 40% (which it was at her lowest point; after being nerfed right before her rework dropped).
They made it so she no longer has to detach and she’s no longer able to switch allies, effectively speaking, by tying her abilities effectiveness into a very clunky best friend mechanic. This removed much of the counterplay of the champion, as she now has zero reason to put herself at risk, while also anchoring her to one person and enforcing her identity as an afk duoQ champ.
In the process of removing all the fun from Yuumi to make her easier, Riot’s goal was just to get her out of professional play and into the hands of low elo players who don’t wanna move around much and just want to be a cute cat supporting their friends. Did it work?
Absolutely not! Her winrate is still bottom tier because she went right back into pro play and had to be nerfed all over again. And by removing skill expression from the champion, did they make her any easier? I guess, but her mastery curve is still the 21st in the entire game, the closest enchanter to her in difficulty in this sense is Renata Glasc, who is in 44th place. In the lowest elos possible, her winrate has somehow gotten even worse than before and she now sits at almost 40% WR in Iron. She is genuinely unplayable for low elo players, both difficult to learn and useless to master because you get no returns from putting in the work.
You basically have to break your back learning to optimize every drop of power from the worst kit in League of Legends in exchange for a mediocre WR with Yuumi, when you could instead just play any other enchanter and do far better.
Trying to balance her around a low skill floor is a terrible idea to begin with, this entire plan was doomed from the start. Yuumi is a role-altering champion who does not teach you the fundamentals of League. Beginner friendly champs always have been, and always will be, fundamentals-only champs, with almost no mechanics unique to them on top of that. Garen, Soraka, these are beginner champions.
Yuumi is more akin to Ivern or Singed in that she’s a champion who’s mastery is unique to herself and will not help you improve at anything besides playing Yuumi. Champions like these always reward basically one tricking them and end up with low play rates because of it, even if they’re mechanically simple and powerful (see Ivern). So balancing Yuumi around being an all-inclusive enchanter for beginners is a horrible idea, and the data backs it up, beginners cannot play Yuumi. Low elo players cannot play Yuumi. But she’s so nerfed that Yuumi mains and pros also cannot play Yuumi, so what’s left? Who is this champion for?
The rework simultaneously removed her counterplay and removed her power, so she’s less satisfying for both sides, and less healthy for the game as a whole. What is she even supposed to do anymore? Her healing and shielding is bad. She offers little to no crowd control. Her damage is bad. Her unique remaining niche is basically just being able to support dive carries like Zeri or Twitch, who can get into weird positions with a Yuumi where other supports would struggle to follow and help them, but is that really all an entire champion should offer? She can’t even do that with non-adcs anymore because of the dumb best friend mechanic, and the changes to her kit to where she now empowers specifically auto attacks instead of giving stats, and that empowerment scales with your ally’s crit, trying so hard to make sure you cannot get creative with who she’s paired with. Because of that, even slightly non traditional adcs like Lethality Varus can’t benefit from these buffs.
They need to revert this rework and balance Yuumi with the intention of her being a low playrate niche champion with a high skill floor, it’s the only way she can remain functional. It’s not what they wanted her to be, but clearly she’s failed at what they wanted her to be, so what else can they do?
Yuumi’s entire design is a mistake. It’s not a surprise that they can’t properly rework the awful concept. Can anyone even explain why a player should be able to acquire a high rank without having to have their hands on a keyboard? It’s crazy because if you think of Abathur’s design, who essentially gets a Yuumi-esque ability, he is completely fair and balanced. He can be killed; he requires macro and micro decision making to succeed; he requires constant map awareness; his abilities have counterplay; and his ultimate forces him to have other in-game knowledge.
Seeing this, what the fuck is Yuumi aside from pure buffing through scaling and E alone. I mean that was her entire kit pre-rework. Her Q and R are annoying to deal with, but it’s the massive E healing, buffing and shielding that fucked you up and you couldn’t kill Yuumi to stop it.