At the end of the day, the AD position is a glorified recruiting/vetting position with some PR thrown in. Sports is a talent business, and AD is just the top of the pyramid. AD has to hire/vet good coaches for each sport, each coach hires/vets good assistants, coaches recruit good players.
Just based on the recruiting departments for different companies/firms that I've interacted with, the best recruiting departments tend to be those who have seen the best talent over and over again. If you do that, you know what to look for. If you've only dealt with mediocre/average people, anyone who is average/above-average is going to look great to you. Problem is, average/above-average doesn't cut it at Texas.
Given CDC's experience, I don't think he'd know a great head coach if that coach slapped him in the face. Average/above-average? Sure. I'm sure someone will throw out Patterson as some meaningless example here, but CDC didn't hire Patterson. I actually think Sark could pan out here, but I attribute that to luck more than CDC's brilliance. And some weird pride situation going on where CDC wants to get "credit" for picking the right coach to turn the program around (not some proven person like Urban).