did the jax nerfs do anything?

they did jack shit

He is around 50% winrate, as are multiple other champions. His winrate in jungle dropped about 3% going from 9.1 to 9.2, and his top winrate went down from 50% to 48.5% so something has happened, although it's still quite early in this patch. Next patch the change of Essence Reaver will affect him, and if Riot goes through with removing/replacing Conqueror that will hurt him as well. Jax is a strong champion right now I'll admit it, but there is a ton of stuff that can shut him down effectively if you just know how to play against him.