Baraka is underrated in my opinion. no he's not top tier, but many people lump him and Reptile together as being the 2 worst. this is not the case, as Baraka proves in this matchup. I love this match- Baraka is a favorite of mine, and I think he is one of the best picks against Jax.
1. Every character has to be aggressive against Jax to win. With Baraka's awesome sweep and JK, excellent CQC, and fast walk, getting in Jax's face shouldn't be too much trouble. Constantly pressure Jax by mixing up sweeps and JKs. Jax cannot HK Baraka out of JKs like he can most everyone else. Baraka's JP is even harder to anti-air, so mix that in as well (it's also great at getting over Jax's wave punch). Apply pressure with double kicks (HK in close), blade swipes, and crouch punches. Baraka has the best crouch punch in the game. you can rattle off 3-4 in about a second. Most likely a good Jax will never jump at you, but if he does, be ready with Baraka's blade fury, or an AA roundhouse.
2. Jax must stay away from Baraka to win this match. If he does keep distance, Baraka has little chance. There aren't many characters that can beat Jax from afar. A good Baraka will always be trying to get in. If you're far away and Baraka is coming at you, try to time ground pounds at the right moment Baraka lands on the ground while he's jumping towards you. Also a HK right after Baraka lands will often times hit him. Anticipate Baraka's jumps and backbreak him.
3. Baraka has some of the best CQC in the game, and he is able to punish Jax nicely up close. Advantage Baraka.
Overall, probably a 6-4 match in Jax's favor. I just played Scorpangel this week. He has the best Jax out there right now, but my Baraka was able to get him 2 out of 3. So it's definitely winnable.