@RiotGames: Yasuo isn't the problem, it's the build.
In the past there have been many champions who are supposed to build damage but instead build tank because it's simply better on them. Take for example, tank Ekko, or tank Fizz. Now, those champions are AP assassins, with high mobility and alternative damage built into their kit (damage over time and damage stacking passive).
Yasuo is an AD/Crit fighter assassin - his regular build focuses on building up to 100% crit chance and then start building AD items. In the past few patches, the only couple of changes have been made to Yasuo, most notably, a few bug fixes a patch or two ago.
Tank Yasuo is a build that takes advantage of Yasuo's high damage with Fervor of Battle stacking - you take 29% AS runes, Fervor of Battle, and builds 
or 
into 
with 
. This allows for Yasuo to still have sufficient damage and tank stats because of the attack speed he has from Runes and Triforce/PD. The other items just offer him tank stats.
The reason I brought up champions like Ekko and Fizz is because they've had a problem in recent patches, where building tank on them is just generally better than the build they were intended to build. Riot's response to builds like this were nerfs - not to the items, but the champion. It's reasonable that they would do that, but I feel like they're hitting it in the wrong spot. Yes, the way they went about it was good, by nerfing the aspects that were strong in the tank build, but those nerfs can still affect the "regular" playstyle of building AP. My guess is that Riot doesn't want to just nerf the tank items because it'll hurt tanks, but what hasn't been mentioned is that tanks still do a lot of damage for being mountains of health sitting in the enemy team. Tank items have a lot of utility at their disposal - Frozen Mallet offers a bunch of health as well as a slowing passive, Sunfire Cape offers a constant aura of damage around the tank (so yes, damage!), Sterak's Gauge is all around a good item for health, AD, and servivability. Rylai's Crystal Scepter and Rod of Ages, which are seen in almost every AP tank build, as well as both AP items, offer large amounts of AP and a good amount of health. They both have utility - Rylai's has a slowing passive, RoA grants mana from damage taken (correct me if I'm wrong).
My analysis is that tank items, while offering health, also gives a good amount of damage/utility that can be abused by assassin-type chamions not because the assassin-type champions are too strong, but because they already have utility such as gap closers and defenses built into their kit. Tank builds are problematic because many items that accommodate both AP and AD champions have too much utility at their disposal, whilst still granting tankiness and damage.
I doubt a Rioter will respond, but it was something I thought was worth mentioning.
EDIT: ArKaDaTa (EUW Challenger Yasuo OTP) made a post that accredited much of the build's damage to Fervor of Battle. However, he said, it wouldn't be practical to nerf that because it would impact other champions who have nothing to do with tank builds.
There's many ways of going about nerfing tank Yasuo, but I just find it annoying how Riot is going through and nerfing champions who abuse tank builds one by one, and not just fixing the problem altogether and nerfing the tank items.
