Tanney did virtually nothing in the first 2 preseason games. He completed 45.5% of his passes in the first game with a passer rating of 61.9. He was 1-6 in the second game and had a passer rating of 39.6 and now after one good game playing behind the starting OL for a series vs scrubs you have some wanting to dump Orton for him.
I'm not saying Tanney doesn't have some potential but some need to slam on the brakes. No way do you dump a solid backup QB who's only 31 years old for a QB who's played against nothing but scrubs and has never started a regular season NFL game. We would be holding our breath with every hit Romo takes.
If the Cowboys left themselves with an inexperienced backup QB who's never played against quality competition in a regular season game and Romo were to go down 5-6 games the season would be over! At least an experienced QB like Orton can possibly keep you afloat for a few games until Romo returns. Tanney vs RG3, Peyton Manning and Drew Brees would be ugly.