Well, the easy answer is that Oklahoma only has 1 loss, and 2 wins over ranked teams while Texas has 2 losses and only 1 good win(over OU). Also Texas lost its 2 games on national TV, EVERYONE saw those losses, and very few people outside of Texas has seen any of their games since other than the Oklahoma game. That's the nature of the human polls, it's not necessarily what you do, it's also how many people see you do it. That's something the Pac 12 has been bitching about for years with their games being so late that a lot of the national media doesn't see them.
Texas's conference schedule so far has been the absolute dregs of the Big 12(other than OU). Wins against kansas, kansas st, Iowa, and TCU don't really impress anyone(not to mention they needed one of the worst blown calls in recent memory to beat Iowa State, who may be the worst team in the B12 this year) Their last 3 weeks will really show us what Texas really is, ending their season against Okie lite, Baylor, and Texas Tech.