There has to be underlying problems with Shaco
So its no surprise Shaco is back to 54-56% win rate depending on what site you want to use.
There is an underlying issue with this however. You see, Shaco's base damages are extremely low. Shaco is outright terrible until you get items. So how is a champion with very low base damages the best assassin in the game? Well lets take a look at some things. First, his new core build:

Duskblade shouldn't be a surprise considering his stealth. Honestly its probably the least problematic by itself out of the three.
We then have EoN. This item is especially problematic on him because he can channel the spellshield entirely during the duration of his stealth. There still is no real way to counter said stealth so what you get is Shaco popping out of 4.5 seconds of invisibility with a spellshield up with gives you very little room to react.
IE is problematic because his Q + Backstab is a guaranteed crit, so IE actually amplifies the damage of it. Honestly its starting to come to light that the mechanic of guaranteed crits is becoming an issue when stacked with lethality.
So what do we make of this? Are the items too strong? Maybe EoN still is a bit even after the hotfix. The other two I dont feel are out of line however. We've also covered the fact that Shaco has pretty terrible base damages as well
So the only thing thats left is the method of delivery. Shaco's kit is just toxic. Theres no other way a champ could have their base numbers gutted so hard and still remain above a 55% win rate. Honestly I think this comes down to the removal of counterplay to the invisibility mechanic.
It's quite apparent it's going to take something more than numbers tweeks to reign him in again