First off Washington has not been a perennial bottom dweller and has won a BCS bowl in 2001. They had a down stretch due to a bad coaching hire, but everyone experiences that at one point or another.
And in the BCS era the Pac has done just fine.
The Pac has the second highest percentage in BCS games for power conferences next to only the SEC.
Up until this year in the BCS era, the Pac-12 has had a winning record against every single BCS conference except the Big 12.
This is a bad year for the Pac and for Utah, but the Pac has done just fine.