Tactically he isn't the greatest IGL. The reason I feel he would work better in Na'Vi is their current play style. They are more focused on defaults and relying on their aim, and raw talent to get them openings. Ange1 is great in those situations because as an IGL he has some amazing fragging potential. Drastically better than Zeus in that measure. Na'Vi currently isn't a team that should be micromanaged or overly tactical, which are Zeus's IGL styles. They've been doing much better with a more loose style which Ange1 will compliment more.
These are the two games yesterday vs. fnatic:
His rating for the last 3 months currently is 1.18. And on top of all of that, he has clutch potential. I just feel he would be a better fit for the team with their current setup.