I disagree with a lot of what's here. It's not a "decent" coach; it's a "right" head coach. Charlie Strong was a decent head coach who didn't have a prayer of succeeding there from the moment he was hired BECAUSE of that infrastructure there that you tout so much. Because while that infrastructure will give the football team everything it needs to compete, it also meddles like nothing other. And not only do most of Texas' recruits have an entitled attitude from the moment they step foot on campus, that infrastructure only enables the entitled attitude further. In other words, while Texas has every advantage a college program could possibly have, they have a massive culture problem - and one that won't be solved by a "decent" head coach. You'd have to have an excellent football coach that can shut down meddling and manage ego - and outside of a Nick Saban-type coach (which, sorry - Sark ain't it), I'm not sure just any coach can do that at a program like Texas.
And this is all assuming they had stayed in the Big 12. The fact that starting next year they're playing in the SEC is going to make that problem a whole lot worse. If a school like A&M, one that has a lot of the same advantages and problems that Texas has, has only been slightly better than "also ran" at any given time, what makes you think Texas will succeed where they haven't? I mean, there's the reason why there's the joke "if Texas can't win in the Big 12, they might as well head to the SEC and get paid better for not winning" exists.