Another factor is that Manning did it against the defending SB champs in the Ravens, before everyone realized the Ravens aren't any good, and Foles did it against the Oakland Raiders who everyone knew they haven't been any good for a long time.
My gosh, the Raiders struggled to beat the Steelers at home, shows how bad they really are.
And, Foles plays for a team who is run by "Chip". Any team run by a Chip is forever relegated to second-class status. If Chip would get his hair trimmed into that "Spock" look that Tomlin sports, they might relegate the Eagles to the Atlantic-10. If you are a "Chip", you need a more manly buzz cut than the Spock.