Mr Cowboy;2362119 said:
Danny White by a long shot......followed by Craig Morton, Beurlein and Romo.
To me, a backup is not a player who eventually started long-term, more like a Don Strock used to be for the Dolphins.
If that's the qualifier, that eliminates White who did not log much action unless he was a temporary injury replacement for Staubach or had a start or two late in the season (as he did in a few games in the late 1970s). I would also eliminate Morton and Romo for that same reason.
Steve Beuerlein fits the best. He was never a long-term starter and came in as a reserve to get us through injuries to Aikman. Others were Garrett, Bernie Kosar and Rodney Peete. Clint Longley fits also, even if he was a simple flash in the pan.
And I am disgusted that Ryan Leaf is not getting more play. The same goes for Clint Stoerner. I won't even get into Kevin Sweeney and Reggie Collier, I would just get too upset.