"Yasuo is overpowered and takes no skill to play, just wind wall in a random direction blahblahblah"
That's why he has 46% winrate: http://champion.gg/champion/Yasuo/Middle
"His pick rate is high that is why his winrate is low": http://champion.gg/statistics/#?roleSort=&sortBy=general.playPercent&order=descend
There are 14 champions that are more popular than Yasuo, they all have a considerably higher win rate.
He was only good when the bloodlust mastery worked on creeps, now he is a struggling melee hero with flashy animations that makes noobs think he is OP.