Karrigan is excellent out of game. He is still involved in prep tactics afaik. And he has a strong mentality which isn't swayed by playing with a bunch of star players.
They should fetch Fallen if they are looking for IGL, give him an offer he can't refuse. He has the mentality to lead superstars. But I can imagine that he might not want to be viewed as a traitor of any sorts. If he succeed in Faze, his rep would take a slight hit in Brazil. If he fails, his reputation would take a gigantic hit.