Alias - Or as I like to call it, who the hell am I watching?

In deference to my father, who I know reads this blog dutifully and probably hasn't watched his DVR'd Alias yet, I will not spill anything from last night's episode beyond the opening credits. Correct me if I'm wrong, but nearly everyone pictured in the credits for this season is brand new save Jennifer Garner and Victor Garber. When did one my favorite shows sustain a mass exodus? And further, why wasn't I properly notified?