There's a few points I want to make here.
Chris Mortensen shares an agent with Eagles head coach Chip Kelly. When Kelly accepted the position with Philadelphia last January, Mortensen was the first one to report the news, in what Adam Schefter called the "scoop of the year". This information seems valid and trustworthy.
The Eagles did not choose Mark Sanchez over Michael Vick. I've seen so many tweets saying, "how could Chip Kelly choose Sanchez over Vick?" Let's get one thing straight, Michael Vick was in search of an opportunity to win a starting job. With Nick Foles fully entrenched as the Eagles QB, Philadelphia simply couldn't offer him that opportunity. Chip Kelly would've loved to have Vick back with the team, but he simply deserved an opportunity to start in New York.
I understand Sanchez was a polarizing figure in New York, I understand his 2012 was pretty awful, and I understand he committed an act infamously known as the "butt-fumble". But what I also understand is the guy has shown he can win in the National Football League.
As a starter in New York, Sanchez compiled a record of 33-29 in four seasons. He also had a 4-2 record in the playoffs, all four wins coming on the road which tied an NFL record. In those six playoff games Sanchez had a combined 94 QB rating.
People make the case that the defense carried Sanchez and the offense to those victories, which is fair. But it's essential to understand that the offensive roster in New York was far from potent. In 2012, New York scared defenses with an offensive stable consisting of Jeremy Kerley, rookie Stephen Hill, Chaz Schilens, Dustin Keller and Shonn Greene. I don't know many quarterbacks who can light up the stat sheet with those weapons.
My last point is that the Eagles have a very strong offensive coaching staff. Chip Kelly, Pat Shurmur and Bill Musgrave should be able to develop Sanchez into a better player. Taken fifth overall in the 2009 NFL Draft, Sanchez has the physical tools to be a good player. He's also only 27 years old.
Sanchez is here to compete for a backup role with Matt Barkley. There's a good chance that he never sees the field during the regular season, and that would be a positive thing. However, if Nick Foles were to go down, Sanchez provides an experienced option who could lead the team to victory.