I think the problem is more "Why Shaco?"
He has been a borderline garbage pick since season 3, and although he might have a 53% winrate, he has a very lowe play rate, and a very niche pick.
He is also countered very hard by the most played champ, the cancer on two legs they call "Lee Sin"
Looking here on 13-12-16
He is currently the 24th highest win rate champ/role. If you are going to use win rates as a method of determining who needs nerfing, then clearly 23 other people need nerfs before him.
He also has a 5% pick rate, with a playerbase average games of over 100. This shows that compared to other champs, the people who play Shaco are going to have more expertise than someone who randomly picks the flavor of the month.
Then we take a look at Yasuo Top. 51% win rate, 11% play rate and a 40% ban rate.
This indicates a problem, because his pick rate AND win rate are both higher than average, and has a ban rate to show it.
A high win rate with a low play rate and high loyalty of players indicates that shitters aren't playing him. Only people who understand him are playing him.
Everyone picks Yasuo. A lot of them are bad. They suck from inexperience and lower his winrate.