Seriously? These two situations are comparable?
1. Kurt Warner does not have a consecutive games played streak. Brett Favre was not coming back to compete for a job. His ego would not allow that. Anybody who suggests otherwise is delusional or disingenuous. Additionally, it would be unfair for the Packers to say to Brett, "Well, you've been our starting QB for 15 years, but now you have to compete for your job." It just doesn't work like that in the NFL.
2. Matt Leinart and Aaron Rodgers are in different situations. If the Pack had not played Rodgers this year they would, in all likelihood, have lost him to free agency. The same cannot be said of the Prince of LA.
3. The Packer's atrocious defense and spotty running game would not have improved with Brett at QB. The Pack missed the playoffs because of those inadequacies, not because of poor QB play.
So I ask myself the question, "Would the Packers have been in the same position as the Cardinals with Favre (as the starter) and Rodgers (as the backup), if they would have adhered to the same fundamental concept of competition, "We'll play the best players and the quarterback who gives us the best chance of having success in 2008"?