"His gameplay does not need a rework."
Jax has one of the most stale, one sided, predictable playstyles in the game. For someone who is a "Grandmaster of arms" he feels more like an eggplant helicopter. I know what Jax is going to do as soon as i see him. He will activate his Counter Strike (helicopter), jump on me, stun me, and proceed to maul me without me having a chance to fight back or defend, because i am stunned for 2 seconds. Alot of people complain Pantheon's design is horrible, but this is just as toxic and outdated.
And let's not get started on his ultimate, which basically gives him free Armor and MR for building AD and AP. This is probably one of the most lazy and unimaginative ultimate designs in the game.
RIot should definitely give Jax a Fiora level of rework. Before she was just another Xin Zhao copy. Now she is a completely unique champion with a very demanding skill level. With defined strenghts and weakneses.
Also, i would suggest RIot doing a bit of a clean up on Jax's scalings. For what appears to be an AD autoattack reliant champion he has too much unnecessary AP scalings that just don't fit in with this character.
http://www.auplod.com/u/dpoula9d885.png