The Jax nerf was nice, but he still needs more.
I don't usually play Jax, look at this game, however...
There was nothing the enemy team could do, I jumped on them and they got stunned, followed by my W and auto, this combo nearly killed them with 0 counterplay they could offer. Teamfights are literally easy mode as you burst everything down despite being focused, combine this with the rest of your team and you've got an unstoppable killing machine.
Mind you, the build I was using as Jax was an experimental build, if I tryharded and got conqueror, hydra, etc then it would be absolutely fatal.
So, I propose to simply decrease his AS and up the cooldown on his W, this could easily get him where he belongs.