A few points to make:
After learning how to play against Yasuo I've found that playing against him the "right way", which is just to be passive and sit at your turret until you run out of mana, isn't really fun for either Yasuo or the opposing midlaner. At some point you have to back and if you didn't take teleport, you just lose your turret.
Yas is very viable in every lane. Why is that and why should that be?
His ban rate probably doesn't account for the number of times he was banned by both teams, just the number of games he was banned from. Nor does it account for the number of dodges after he got picked and some player decided shitgame, next.