I am a long time Bills fan but also an Eagles fan since I have now lived in the Philly area now since '99.
I attended 2 games here this year in Philly. A few things to know about the Eagles offense and Foles before he was hurt:
The O Line has been a mess due to injuries and suspensions. I dont have the stat but I think the starting 5 have only played 1 maybe 2 games together
In my view, Shady lost too much weight in the off season. He still has explosion, but its obvious he lost some of his power / strength so to speak
Foles has started a total of 24 games in his career
In the opener vs JAX then again vs STL, there was one issue that was so obvious, it stood out like a sore thumb. No Desean Jackson. Defenses have not been respecting the deep long ball or team speed. With that, defenses have also been keeping defenders closer to the LOS which affects Sahdy (See above)
All this said, i would take Foles in a heart beat. He is a good team mate, very smart, has a good pocket awareness and yes has a canon for an arm. The Bill still need to do something about Hackett as the OC however.