By that logic, Brady's MVPs should be taken away because the Patriots still won with Cassel, Garappolo and Brissett.
Pederson has simplified the offense for Foles and he's not being asked to do as much as Wentz. They've also been able to lean heavily on Ajayi, Blount, and the stacked defense. It's basically a rerun of Struggle Wilson's career. Wentz is still the real MVP.