KDA isn't too important on Yasuo, of course if you snowball you kill everyone, but it's like that for every champion. For Yasuo if you get behind you just play safe and farm. Top lane is perfect for that because Top is an island. so you get all the farm you want.
Just know that to win you will need to successfully outplay and out manuver most of your opponents.

With this build you gain a lot of HP while still capping the stats you need to (crit, attack speed). You become a lot harder to kill while gaining more utility to kite, chase, and duel. Also all the items in this build work together and make themselves all a lot stronger.

You will deal less damage then you would with a normal Yasuo Mid Build but this build will grant you more utility, tank stats, and still a ton of damage.

My main tip which you will learn after playing Yasuo a lot is knowing when you can and cannot go in, be aggressive, etc. That is something that a guide can't really teach you and it's something you will learn by yourself.

-Try to E through minions before you E to your opponent to maximize the damage your E will deal.

-Dashing to minions beside your opponent to get in range to Q them is a good poking tool

-While engaging in lane you can save your E dash to your opponent for when you need to close the gap between you too a bit more or for some extra damage.

-During team fights don't be the engage unless you have a great opportunity (you land a 3+ man knock up or something) you want to be the strong follow up

-Try to pick people off before the fight because you're great at doing that and dueling

-Look at videos for Yasuo Jungle Jumping, where you E through a jungle creep to go over a wall, it's quite useful when you're escaping through the jungle

Thank you for checking out my guide and I hope it helped you out.