Sorry if this goes OT, but as much as I am a Favre fan he was NOT considered a "good backup" when he was in Atlanta. He was a young QB with a lot of physical tools who partied too much.
From Wikipedia:
Had he stayed in Atlanta, he would have partied himself right out of the league in a couple of years. Luckily for Favre and all Packer fans, Wolf took a chance and Holmgren tamed him a little bit. Now he's headed to the HoF.
Also, the Packers had a guy named Matt Hasselbeck, who looked promising in preseason games. They traded him for a first rounder rather than lose him as a FA, used that pick on Jamal Reynolds, and the rest is history.