Now, don't over react here
Honestly, does anyone else thing yas needs a small nerf in his passive? He's honestly in a fairly good spot, but just a tweak to his crit damage reduction considering he only needs 2 crit items to have 100% with runes. I mean, all things accounted for 10% cirt damage reductions is a pretty negligible. I'd say try 15% and see if it makes enough difference late game to balance out his really strong early game.
People just don't really know how to play against his mobility. You have to let him push you under the turret, and get your jungler to gank, because Yasuo is bad at escaping ganks.