How about you shut your mouth and use your brain (If you have one).
Do you really think that if Yasuo was op he wouldn't be played every game in pro play, or else, banned in every pro game? Unless you're better than the pros?
I'm gonna guess you're salty due to this game: http://prntscr.com/dsl2yd.
Let me just point out something else. Your MMR is Bronze/Low Silver. You have NO fucking right to say if a champ is overpowered or not. You have the game knowledge that is 1/1000 of a pro player.
I'm shit at League as well, (only gold LUL) but you have to understand that annoying to play against and broken are 2 different things. You will have games where the enemy Yasuo gets fed and you'll have games where your Yasuo will get fed.
But we can say the same thing for Riven, Darius, Vayne, Jayce, Yi, pretty much any champ that is made to do a lot of damage. If they're fed, they will kill you unless you CC them.
I'm sorry, but the guy has a 50.04% winrate (if you average out the top and mid winrates). He is NOT op. Frustrating to play against? In some cases, yes. But please don't go on gameplay balance and complain about a champ that's not OP. Thanks.