I'm going to officially eat crow:
Jak does not need a buff.
I'd argue that Jak desperately needs a buff. He's not complete trash but when you look at his reveal trailer and early gameplay, you can see he was a real beast who had a wide variety of amazing guns (for example, did you know his gravity gun used to have larger range and was a Level 1 hit confirm?) whereas now he's a pretty predictable character who mostly relies on constantly moving around, spamming his yellow gun on the ground and red charge gun in the air. He needs his other guns to actually be options, like Ratchet's, rather than situational things that are rarely useful.
Speaking of characters that need a buff, didn't Omar say that Nariko was his favorite character in the game? Then why is she so bad!? Allow me to explain: like Dante and Raiden, she is a combo-oriented character. Unlike Dante and Raiden, she has awful AP gain so unless you're able to do her long combos without being interrupted, you're probably never reaching Level 3. And you pretty much need to, since her other supers are horrible. Her Level 1 has her firing a slow, telegraphed barrel blast at the opponents, which nobody will fall for unless you're really lucky or you've done a hit confirm with her projectile - unfortunately this requires some strict spacing and usually flat ground, since her barrel gets weird on sloped surfaces. And her Level 2 has the honor of being possibly THE worst Level 2 in the game, with only Sweet Tooth's missile to challenge it. She gets on a huge cannon and fires cannonballs at her opponents! Sounds great, and it would be great - except literally all they have to do to dodge it is STAND NEXT TO HER. Seriously, as long as they run next to her she has no way of hitting them for the duration of the super - not only that, but they can kill her while she's a sitting duck as well!
The only things she really needs to be completely viable and balanced is slightly better AP gain/lower AP requirements, and either a buffed Level 1 or Level 2 (faster start up time or a way to kill opponents standing right next to you, respectively.)