It's not the player, it's the system. Despite consistently being in the top 10 in passing offense every year, Texas Tech has had ONE QB drafted in the past 10 years, and 3 in the past 20. The jury is still out on Mahomes, but it's not a reach to say that their success is more on the system than the player. You're not wrong with your last sentence, but that's the thing: TTU's and other air raid teams' offenses are designed to put minimal pressure and decision making on the QB, which allows even average guys to thrive with them.