As someone who plays Yasuo a lot and main him, with 650k+ exp on him, let me tell you he is balanced. Don't you dare try to nerf him. He can't even play event mode games because he is so weak on them. All the champions with stuns, knock ups/backs, slows etc. counter him. He is squishy and once stunned he is done. On top of that Yasuo is easily countered in lane, unless you're bronze.
For example, having played him for years, I went up against Jax, who just got a buff mind you. I exhausted Jax, ignited jax, activated ghost blade, used bork on him, threw my tornado at him and caught him during his mid jump, ulted him, and then he auto attacked me to death. Why? because Yasuo isn't broken like almost every other champion.
As a Yasuo, you can't engage, only when extremely fed will Yasuo engage. Even though he is a fighter, you won't see him run into team fights. He gets obliterated, He is squishy. He can't do much more than passively wait. If you are good with him and can use the map and hit kit well, it's different, but only the dumbest Yasuo will charge into engage first.
His Q takes three hits to activate. Three. That's already bad enough. And you want to nerf Yasuo again? No shew go away.