Yeah, that's in the Coaches section. You would be given a certain amount of time to work on plays depending on how good your coaches are. That would making hiring coaches matter a little more. I've never played a game where coaches matter.
I am in agreement with the idea that you wouldn't want a QB to come in and have few if any passing plays. That's why each play has a rating of it's own and the player has to be at or above that level to run the play. You would have easy passing plays just like you would have easy running plays. It wouldn't be a random thing and would be based on the amount of "action" (guards pulling, stunting, crossing routes, play action, etc.) in the play. The same could apply to defenses as well.
The best thing would be to feel hamstrung by a true freshman coming in and playing. I usually have no fear putting a 4* true freshman in a game because there's so many play options. If he's limited I will have to decide if my steady, more experience Sr. rated at 88 will be better than my income 83 rated hotshot QB (example ratings, of course). If my senior is a 90 on playbook and my freshman is a 40, it will make the decision that much more important.