I agree with Mandel. The Red River Shootout is in a terrible decline. The decline is so bad, it's gotten to the point where the Red River Shootout has been replaced by the Red River Rivalry.
Seriously, though, there's nothing wrong with the state of the Texas-OU game. The 2008 game was an exciting, competitive contest, and both teams are still in the top tier of college football. The only thing that makes the Texas-OU game seem less central to the Big XII Championship is this surge of talent in the North Division (which, as it turns out, didn't change the fact that the winner of Texas-OU won the Big XII Championship).