Now, hear me out, I'm not talking giving him more ad, or higher ratios, but rather, rectifying a mistake they made in regards to him, which is his attack speed.
Yasuo used to run attack speed quints and marks, giving him an increase of 29% attack speed level 1, and along with the 4% from the ferocity tree, he would end up with a 33% attack speed increase level 1.
Currently, the max you could get at level 1 is 21%, assuming you ran precision (along with alacrity) + inspiration. With this combination, you would eventually get 36% attackspeed, but by then it would have been too late for yasuo to make great use of it.
You see, yasuo used to run such high attack speed so that 1. he could cap his q cd earlier with only phantom dancer, and 2. So that he can trade alot better early.
With the current runes, he is pigeonholed into using precision and inspiration if he wants to have a modicum of the early attack speed he used to have, and even more so if he wants to avoid buying attack speed (excluding pd).
The solution for this is simply, give him a higher attack speed increase at level 1 (currently 4%), or make his q less reliant on attack speed to cap its cooldown (He currently needs 111.5% BONUS attack speed to cap).