Without getting too wishlisty, I think HC09's "playbook knowledge" was a good starting point, we always hear about players coming in needing to learn the playbook, more so for some positions. Add player work ethic, morale, team chemistry and some formula where each specific NFL team/Head Coach/coaching staff effect/modify those elements positively or negatively, that's a foundation for a dynamic system for all players, rookies included.
To be clear, I'm suggesting this layered onto what's already in-game like DPP, which should be addressing things like player consistency and traits, that factor in who to start, when and why.