A Godly Anti-Air game. Anti-airing IMO is the single most important aspect in having a great fireball game. The second people respect your AA game and your AA spacing, they will have no choice but to respect your FB game.
Look at every top Sagat you’ve ever played or seen, they rarely, rarely let jump ins go unpunished. They’ll do unconventional ways to AA you(aside from the obvious DP) I.E Kara uppercuts on reaction(not setups), AA tiger shots, AA normals, Air to Airs or even full screen ultra 2(punish every single jump minus characters with teleports and arch changing moves).
I consider my AA game good, and not great, and thats one of the biggest reasons my FB game is far from great. But I am going to grind at it and improve.