This idea just occurred to me, and im actually quite surprised i've never seen this kind of feature in a sim game; but a vital and interesting part of being Coach in the NFL is putting together a weekly gameplan specific to the upcoming opponent. I know this would involve a whole bundle of new features, but hey thatd be fun to see a whole new section.
This would really ratchet up the whole "chess game within the game" angle of football. Rather than having one static playbook the whole season, each team would have some rather large playbook for the whole year, say 100 plays, with each week you pick the 25 most likely to be called that week. You could also add in other features, like some form of scouting performed on the opponent, I dunno, the possibilities seem quite numerous. This would be a feature to set Draft Day further apart from the pack

Oh a side suggestion, a much smaller - ability to easily print out the playbook; i always liked to be able to have a physical copy of the playbook, actually makes it much easier often to see. You can have like 4 plays per sheet, two on each side, which can really enhance how quickly you can see your stuff, and this I think more closely approximates the game where the coach has at least a call sheet in his hands at all times to call the plays from.

It wouldn't involve anything new at all. I do this every week in my solo league. You create playbooks, and in those playbooks you give each play a frequency. Then you put in those playbooks in the down and distance you want them to be used. It's time consuming, but can easily be done within the game as it currently stands.

Im suggesting features be added into the game so you wouldn't have to do things manually and externally

1) Introducing new screens and UI such as a "Gameplan" screen with -
* Playbook of the week
* Scouting sections of your opponent, using some of the logic used when drafting players
* Ability to print playbooks

2) Ability to have quick keys call plays
-each play assigned a number which you could then enter as a way to quick key call any play of any formation, something that could be easily tracked by the printed playbook