The Alamo wanted to be considered a legit 2nd tier bowl. Hard to have that status with a 4th place team. They swapped the Big Ten # 4, often #5 with 2 Big Ten BCS bids for a higher seed Pac Ten team. They really do pay too much money for a 4 or 5 seed.
Also makes the Pac Ten line-up with Rose, Holiday, and Alamo more respectable. So, on credibility grounds it was a good move for the Alamo and the Pac Ten. However, the Alamo might suffer from less travel from the Pac Ten. They are kind of a Rose Bowl or bust league when it comes to travel.