Since the nerfs and bug adjustment Yasuo's win rate has fallen, but he has a high pick rate at the moment and the ban is justifiable just due selection frequency. He has a high play rate across the different Elos and I think any champion that is picked frequently is a justifiable ban.
I am a bit surprised people are not banning
since he is one of the highest picked ADCs at the moment and it seems he either snowballs or stinks the whole game. That is mostly problematic with so many people picking him and most taking the early armor pen build instead of the crit build.
A seasoned
player is virtually unkillable, but most novice players with have a lower win rate with him. Recently, I played against a platinum player who looks like is beginning to pick up Aurelion. He single handedly carried his team to victory in a very long game. He doesn't have a high win rate now, but it typically takes several games in a row to get use to him and after that the win rates jump.
My team had a very difficult time killing him and usually his flash/exhaust/storm/ult were always up when we thought we had a catch on him.