Why do they do that. Nobody cares about a side character who hasn't been seen for 9 episodes having an entire episode. Talk about filler.
I think eventually all the non-savior groups will make an alliance and take over. Probably 2.5 seasons from now. Until then their character and group build up is pretty bad IMO. I mean, an episode featuring Tara?! Fist bump, yo! *cringe*