Because of the space limitation, the red zone is a pressure situation that requires the WRs to be open immediately off the line or set free with misdirection or fakes. Romo usually has to scramble because the menu of Garrett plays are so limited and thus repetitive that blanketing coverage and overloading the O line is frequently an option. Nobody is open until the free runaround time that all the Dallas WRs get after Romo's seven step drop.
The question I always have is: Why are there no identifiable strategic plays conceived in desperation to score and specific to beat the weaknesses of that weeks defense?