First off, Dallas isn't going anywhere this year. Second, if you do plan on going with McGee, do you really think this is the best time to trot him out? He hasn't taken anything besides scout team reps since his HOF preseason.
Third, Kitna isn't the reason why Dallas is losing.
Fourth, Romo was in the Dallas system for three and half years, not three and a half months. You could totally destroy the kid's confidence by asking this much of him this early. It isn't always about one game or even one season.