First off, none of the above has taken into account the scrambling aspect of Vick’s game. Michael Vick has recorded a whopping 306 total rush yards, 9.3 yards per carry, and 2 TD’s. Foles is irrelevant with 3 yards off 6 rushes.
Regardless of how inaccurate Vick can be and how hot Foles’ arm is, Dallas would be in much worse shape having to adjust coverage to keep guys spying on Vick.
Without Vick’s scrambling, the Cowboys now have the luxury to play Philadelphia straight up in coverage like they had success with blanketing Washington.