Considering how bad the Pac 12 looks, I am sure glad their conference champion didn't make the playoffs. The playoff should just be composed of the best teams, and that should be true if the playoff were to be expanded. In an 8 team playoff, no PAC 12 team should have made it.
The unfortunate thing for the Big Ten is that they had three teams that look to be top 8 teams, but I don't think they have any top 4 teams. I have no doubt that that the 4 playoff teams would also easily take care of USC, Washington, and Miami.