But Fang has appeared in the story before, even if not as a party member. She interacts a bit with Snow and is mentioned by Vanille a lot. True, all the drama not related to Oerba happens before, but really, so what? Gang gets plent of focus (hehe) on Gran Pulse, which is why it's really not a problem that she appears later. And when it comes to gameplay, Sky is dead-on.