Yasuo is so OP it is disgusting. I will list why he is OP:
(1) He is not even squishy. For melee champion with high damage his not even squishy because of his passive air shield. You lose trades to him. You land a skill shot and he walks away with no damage because of his shield even if you won the exchange because you landed more damage. Its bullshit. I play a lot of talon and i cant even burst him because of the shield and thats the only thing talon has going for him, being able to burst.
(2) He does a lot of damage. The damage is sustained with AA weaved in with his other abilities or it can be burst after he CC's you. Damagey champs should be weak but his passive shield makes him tanky AND he has burst and sustained damage. Its a rort.
(3) He has CC. The CC isnt even gated by an ability that requires cooldown but he can spam that CC by landing 2 Qs. Which in turn have almost no cooldown themselves. So we have a tanky champ who does high damage of both sustained and burst varieties who also has CC. Great but theres more.
(4) His insane mobility. He Just zips across by using minions. He can even go over walls with it. And again its spammable with no cooldown. He can use this to get away from a losing trade, chase after you forever and ive had this happen where he chases me from the bottom of the screen to the top by minion surfing catches up and kills you. He can use this to dodge skill shots to. So we have a tanky champ, that does shit tonnes of damage either burst or sustained, has CC and now is incredibly mobile. Minions are consistently moving across the screen so his need for minions to be on the screen isnt a strong point. A team mate being with you also means he can zip over to the team mate as if he were a minion. He is still incredibly mobile.
(5) He has no mana. His abilities are spammable and other than his windwall have low cooldowns or no cooldown at all. I mean, they didnt even try to balance this character. The lack of mana means he can just spam his obnoxious kit with everything all day long. Its pretty disgusting.
(6) Turrets dont shoot him when he does his R under a turret. On top of all that he is so special that turrets dont even hit him when his under a tower and his using his R. Even invisble champions get damage. Its just not reasonable on top of his broken kit.
(7) His windwall. This ability is not a problem on its own. Its little different to Braums ice shield. Or Morganas dark shield in many situations but the thing is Braum does not damage unlike Yasuo. He has little mobility compared to Yasuo. Braum is tanky to offset his weaknesses but Yasuo has no weakness. Morgana has CC and is squishy. She does not have the stack tonne of other abilities because that would make her broken and unbalanced. Not so Yasuo. His allowed to have it all.
(8) His ability to double his crit percentage without doing anything because its a passive. The effect this has is give him another ability that no other champ has. Item efficiency. This means the same amount of gold goes a longer way with Yasuo on top of his already busted kit. So he gets more damage for less gold.
It goes without saying no one ability Yasuo has makes him broken but the combination of all his abilities and attributes makes him just completely and laughably broken.
Delete him from the game. He shouldnt be in it. Its amazing he has been able to even exist from a fairness perspective. Just make a giant unkillable hero that can turn on a passive ability that makes him unkillable for an hour while we have Yasuo.