Then surely you know why guys like Kizer, and Beathard, and Peterman, and Hogan, and Hackenberg, and the list goes on and on.... were anywhere from round 2-5.
What exactly are you laughing about? If you claim "yes I do," then you won't laugh, because you'll understand what the NFL really values. You give Mangum an efficient 3000 yd season at 6'3 220 and he wins games and shows an understanding of what he's doing, he's a 5th rnd pick in the 2018 draft. Now, that doesn't mean he'd leave. I don't think he would for that.
The crazy group of people saying that's impossible have no concept of how much the NFL wants guys to understand that type of offense. It is huge. Why do you think Josh Dobbs was drafted so high? Because while he played in a spread at UT and Pittsburgh doesn't, he's crazy smart and surprised them and himself with his knowledge of their type of offense.