TCU will be a significant underdog at Oklahoma State, at West Virginia, at Texas and hosting Oklahoma. But they aren't currently projected as double digit underdogs in any of the four, which does help in their bid for an upset.
There's a reason this wager is offered at plus money. It's not going to happen the majority of the time. But I give it about a 45-percent chance of success, which creates theoretical value and makes it a play.