I've only played a couple games with him (and i'm really bad with him), but i think i understand all his mechanics, i know all his cooldowns, i know how his passive works, etc. I really studied him. Thing is, it's not enough, while it should be: you shouldn't need to play 20-30 games a champ to be able to play against him - and i don't plan playing all champions.
Of course Yasuo has some weaknesses and is possible to outplay. Thing is, i find it really hard at my level (vs yasuo of my level), which is around top silver. The windows to harrass him, for example, are really short: once i proc the shield, i don't have a lot of time to capitalize and do damage on him. Since sometimes he'll also have the windwall, that means i will be able to do full damage once in a while, if he has good positionning, regardless of mine. What i mean is he just need to be out of range or in his ranged minions a few seconds once in a while to be safe, and i find it really hard to capitalize on that.
While he can harrass me a lot if i'm ranged (with e+q, then aa), and all the time if i'm melee. Plus he's AD so he has LS possibilities. That means i feel like he's almost impossible to outtrade (mid, btw, top is another story), or outfarm since he pushes a lot. That would be ok if he was trash lategame or so, but as you said, he's at his strongest lategame
His early game can be strong against the right champion, but more often than not
It's true, my problem is, he's weak against a lot of tops, but strong against most of the mids i play. Kassadin, galio, zed, xerath, etc (and even, in my opinion, akali). I feel like he shouldn't be so strong against so many champs.
Worst than that, if i play kassadin (my main) vs his worst counters (talon, for instance), i still have a shot at winning, if i play smart, and for example i try to outsustain talon, or farm safe under tower. I feel that with kassadin for example, i have no shot AT ALL vs a yasuo. Cause if i trade or all in, 100% chance to die, if i try to outsustain, i lose, if i farm under tower, not only he outfarms me, but he also _outscales _ me.. And i can't even last hit anyway from level 2, or he kills me. The lane feels like kassa or galio vs lee sin - only lee sin doesn't scale at all! I need to know how to have a shot at beating yasuo even when playing a mid that gets countered by him... And i really don't know how to do that, even with your answer.
Otherwise, i can't see how he would be balanced (i'm not saying he's "OP", he's not overpowered per say, more like impossible to balance with his kit i feel). As for winrate, maybe, but yasuo gets shit on by a lot of top and some mids, plus i don't think winrate means much, alone at least.
You certainly want a ranged AP champion to play against him
Well that's a problem. Since when can a melee counter all melee?
You need to be able to position yourself correctly, proc his shield and predict his windwall
As i said, i feel it depends more on his positionning than mine. Unless i have a shitload of range, then he can't dash on me if i stay far from my own minions. I think it must work with brand, annie, etc.
punish him if he does go in for CS
It's only possible when his shield is down, and even then, i feel he can burst half my life if i go in to punish him... Once again, depends on the champ.
Anyway thank you for your answer, i just feel like i still don't know what to do when i face him in blind games and i don't have a proper counter (which is a small minority of midlaners).