Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
A Simple Explanation
I made this guide for Yasuo because I saw the top rated guides were not the optimal ones. Some runes and items the guides tell you to get can easily be replaced with way better items on Yasuo. This isn't a full guide for how to play Yasuo, just so the people that are new to Yasuo know what items to build on him. :)