Now, I'm going to start off by saying that I love Yasuo. However, I feel that he is very binary in his decisions (max E, Q, W, buy PD or Statik first, then either IE or a tank item, then the other as 3rd item). The reason for this is because his E outclasses all his other basic abilities. At the same time, his passive allows for a first item buy (very cheap, I might add) to give him a huge damage output.
The idea that I had was to put the double critical chance passive on his Q, with it scaling with level. This way, it can curb his game up to about level 13. Have it something like "Yasuo's crit chance is multiplied by 20/40/60/80/100".
This way you give choice to a Yasuo player whilst also making his power spike less.... obnoxious. Either the player can max E and dash around, or they can max Q for duelling but lose their mobility.
Yasuo is one of the champions I hear people complain about the most, so I thought I would add my thoughts on how to fine-tune him.
Edit: I understand that at higher elo that Yasuo becomes incredibly difficult to play, so his win rate is reflected in that. This is just a thought that has been floating around in my head for a while. Hell, a counterweight to this weakened early could be a stronger late by removing the damage cap on his crits, but I feel that would make him too obnoxious