Karrigan isn't really an issue in the team as he does his job as an IGL, he just doesn't do it well enough to compete with some of the top teams. There aren't many top IGL's to go around, not everyone is a fallen or a gla1ve. I think without Karrigan they will do just as bad with pretty much any other player (that isn't in SK, G2, Astralis or C9).
Let's say instead of karrigan they had lekr0 or elige or someone like that. I doubt that will improve their team that much if at all, and they probably would have even worse T sides.