I agree that Mendenhall is a very good coach, but to say "without a doubt" they are the best team in the MWC is a bit much. Utah might have something to say about that. Frankly, I think Utah's equally if not more talented than BYU. Utah's problem is their coach is average at best. The Utah/BYU game should be great.
Regarding the TCU game, for me, too hard to call. BYU has played no one this year, in racking up their wins. This is their first semi-legit test. I think BYU is better than the usual BYU team, and I think TCU is worse than the usual TCU team, at least offensively. Home teams have a way of getting up for these weeknight TV games, TCU should be no exception. It's just too close to call for me, but good luck on your pick.