He doesnt have to, what he was refering to , is JG's playcalling system, which went by down and distance, and certain plays were called
in those situations,or a group of plays for each situation.
JG still is involved in the offense, and we still mostly use his playbook, so linehan may be using JG's down and distance system
when calling plays.
However Romo may not follow that like a bkup would, and whenever Romo makes time on a oass play, it is no longer the standard play
it becomes ad lib.
That is part of why when romo wasnt playing the offense did so poorly. It isnt just the skill of the QB.
The other thing is aside from Romo only Moore knew the offense well enough to read defense and run the right play, or the right
throw.
Cassell had very limited time to learn, and that hurt him, and weedon was maybe restricted too much, plus he just goes with the
first option, and whatever was called.