Why you're losing lane (and by extension games) as Yasuo
He's a mid laner. Whenever they've made adjustments to his stats, it has been with his role as a mid laner in mind. He's most easily countered 1v1 by fighters, and most of them make it so he's effectively down an entire ability because they have nothing for him to block.
And why? Because he's an crit-based assassin (as Yi was previously called) who can choose to build a little more defense after his crit to act a little like a fighter. But he doesn't have Tryndamere's ultimate to force himself to survive, nor does he work well with items catered to primary fighters.
If you're going to play him, do yourself a favor and stop trying to go up against Garen and Riven. Hell, you only get to play him half the time thanks to his ban rate anyway, why make it less enjoyable for yourself?
######note: This has nothing to do with the Yas in my last game, it's actually a response to the Yas who dodged champ select right before that guy, since he dodged just because the enemy picked an actual top and mid didn't want to swap.