From watching his film, and I'm no QB guru but I did stay at a Holiday Inn a few times, he looks like a true QB. By that, I mean someone that can read and make the necessary throws required in this offense. Gone are the days of a run first QB that needs tons of help throwing the ball, reading defenses, etc.
This kid has a lot of ability, and he can run, which is a bonus. Not a requirement.
Jameis Winston ran a 4.9 at the NFL combine. He was listed as a dual threat coming out of high school. He's not in the NFL because of his tremendous speed and ability to shake and bake, like Marriota can, Winston's in the NFL because he can make all the throws plus use his legs effectively when needed.