I think a little too much emphasis gets put on things like game plan.
We all know there's obviously a plan before every game and I think we understand that as the game actually plays out that game plan gets altered by many factors, for example, the score - how the defense is playing, injuries, things not working/things working, the clock, etc.. The in game adjustments IMO are where a QB and OC earn their stripes. Clearly it was an issue with Roman and/or Tyrod. This is where an experienced OC is most helpful or detrimental to a QB that is still learning. It takes time for a QB to understand the game where he's comfortable either telling his OC what he thinks or changing the play. I believe this is why Roman was let go - he just wasn't capable of through play calling to overcome Tyrod not totally being ready to run the offense.