Not sure if this is serious, but I will respond anyways.
Steel Tempest's CD scales off AS and proc on hit effects; it is essentially a second AA. 1.3 seconds CD is the cap for Q, and requires more AS than just the 40% from static shiv. At level 9, the CD should be around 1.7 to 2 seconds.
As well, Static shiv cannot be used every 1 second, there is generally a interval for the down time. This passive is especially strong on Yasuo because he can charge it up easily with Qs, AAs, and Es. Also, keep in mind that 270 damage at level 9 isn't that significant. After mitigation stats, at best it would do 1/5 of a target's health.
Yasuo's damage isn't really that special. Statistically, other mADCs, such as Yi and Tryndamere, catches up and surpass Yasuo's damage at full build. It is just that Yasuo gets huge spikes off of Static shiv and IE.
Besides having lower damage late game, Yasuo also has one of the worst base defensive stats. His health is lower than a half of the ranged roster, and he gets no MR per level.
The shield can easily be dealt with with one AA, as it only last one second. Yasuo's only defense against ranged is Wind wall, which he sacrifices a skill slot for.
Overall, he definitely is still very effective in certain match ups, but against another fighter or an AP user with a frequent slow or root, Yasuo is essentially free gold because of his subpar stats.