In the past two years? Yeah, Yasuo has received little in the way of direct nerfs, but the various hits to his items and masteries have been big hits to him when he's been strong. Let's look at his patch history though. The whole thing
V7.2
Sweeping Blade.
Base damage reduced to 60 / 70 / 80 / 90 / 100 from 70 / 90 / 110 / 130 / 150.
NEW EFFECT: Has a 20% bonus AD ratio.
V6.24
Last Breath
BUG FIX: Targeting enemies displacing themselves/each other with Blast Cone Blast Cone.
V6.22
PROJECT: Yasuo
General
BUG FIX: Basic attack animation desynchronized with damage application.
V6.21
PROJECT: Yasuo
Steel Tempest
BUG FIX: Pixelation on third cast's maximum range indicator.
V6.18
Stats
Base attack speed increased to 0.67 from 0.658.
Attack speed growth reduced to 2.5% from 3.2%.
Last Breath
NEW EFFECT: Bonus armor penetration only applies to Yasuo's critical strikes.
BUG FIX: Yasuo dealing a basic attack's worth of extra damage when casting.
V6.17
Last Breath
BUG FIX: First basic attack after casting being delayed if critically striking.
V6.16
Sweeping Blade
BUG FIX: Grasp of the Undying's cooldown refreshing when attempting to cast on a target the dash immunity is still active on.
V6.14
Steel Tempest
BUG FIX: Not always critically striking when Yasuo has 100% critical strike chance.
Wind Wall
BUG FIX: Failing to block projectiles if cast right when Yasuo dies.
Sweeping Blade
sometimes becoming unable to use basic attack after casting.
ignoring both cooldown (regular and per target) and cast time if used while displaced and on on multiple targets.
Last Breath
BUG FIX: Yasuo sometimes becoming unable to use basic attack after casting.
V6.2
Steel Tempest
BUG FIX: Third cast and casts during Sweeping Blade.png Sweeping Blade bypassing Banshee's Veil item.png spell shields in certain situations.
Wind Wall
BUG FIX: Ceasing to block projectiles if Yasuo dies while active.
V6.1
Wind Wall
BUG FIX: Being bypassed by certain unit-targeted abilities (Pick a Card.png Pick a Card) as it spawns.
V5.14
Steel Tempest
BUG FIX: Third cast not applying on-hit effects.
V5.8
\Way of the Wanderer
Flow generation reduced to 1 stack per 59 / 52 / 46 units from 1 per 46 at all levels.
Shield strength increased to 100 - 510 (based on level) from 60 - 470 (based on level).
V4.21
Stats
Base movement speed increased to 345 from 340.
Steel Tempest
Cooldown reduced to 4 seconds at all ranks from 5 / 4.75 / 4.5 / 4.25 / 4.
V4.18
Stats
Base health lowered to 462 from 512.
Base movement speed lowered to 340 from 350.**
V4.17
Steel Tempest
BUG FIX: Going on a shorter cooldown if cast during Sweeping Blade.
V4.13
Way of the Wanderer
Shield duration reduced to 1 second from 1.5.
Steel Tempest
Minimum cast time increased to 0.18 seconds from 0.13.
Cooldown reduction from attack speed reduced (maximum amount needed for minimum cast time unchanged).
BUG FIX: Third cast dealing instant damage in first cast range when used in quick succession.
Wind Wall
REMOVED: Passive bonus Flow per Sweeping Blade.png Sweeping Blade cast.
V4.12
Sweeping Blade
BUG FIX: Sometimes not triggering Spellblade.
V4.11
Sweeping Blade
Maximum bonus damage reduced to 50% at 2 stacks from 100% at 4.
V4.5
Stats
Base armor increased to 19 from 15.
V4.3
Way of the Wanderer
Shield strength reduced to 60 - 470 (based on level) from 60 - 690 (based on level).
Shield duration reduced to 1.5 seconds from 2.
V4.2
Way of the Wanderer
Flow generation reduced to 1 stack per 46 units from 1 per 40.
Steel Tempest
NEW EFFECT: Displays a maximum range indicator while third cast is available.
Wind Wall
Passive bonus Flow stacks per Sweeping Blade.png Sweeping Blade cast reduced to 3 / 6 / 9 / 12 / 15 from 4 / 8 / 12 / 16 / 20.
Last Breath
Range reduced to 1200 from 1300.
V4.1
Way of the Wanderer
NEW EFFECT: 10% reduced damage applies to Statikk Shiv
Steel Tempest
NEW EFFECT: Third cast uses smart casting by default.
Interaction with Sweeping Blade updated for reliability.
Wind Wall
REMOVED: Blocking allied Dark Spheres.
Last Breath
NEW EFFECT: Grants maximum Flow on cast.
Animation time reduced by 0.1 seconds.
BUG FIX: Yasuo blinking to targets who Flash.png flashed out of a displacement's target location right before being hit.
BUG FIX: Cooldown timer tracking error in HUD and Spectator Mode.
V3.15
Added.
These are a more than a few nerfs, yo.