Yuumi is weak at the moment, but also suffers from ACTUALLY being a late-game champ w/ a weak early game.
People are also still picking flash on her as a standard pick instead of highly situational.
People are getting better at exploiting the fact that Yuumi can get down to 90hp and just be in stasis for as long as she wants, and how much psychological pressure that puts on the people who are laning against her.
Still incredibly weak as a lane support, but can be rather frustrating to play against.
Becomes a real thorn in her opponent's side once she gets to the part of the game where she's strong (few items on her and the teamfights are no longer small skirmishes), or even just once she can roam w/ someone who has a decent lead.
A few more tweaks and she'll probably be a balanced champion that is w/ the bottom 20 champs in terms of pickrate, but has a rather high "100+ games" winrate.
Lolalytics Winrate/Minute - Yuumi
https://i.imgur.com/CGyp35p.png[]