I don't see this at all.
The performance wasn't as dominant as other games, but it was still strong and easily enough to win if the offense had performed.
Instead the offense kept putting the defense in hole the first half. Certainly, with the Eagles first TD drive the Cowboy defense failed, but the next 3 scores came after the Cowboy offense gave the Philly offense the ball in Cowboy territory. In 3 straight possessions the Cowboy offense had an INT, turnover on downs and another INT, and the Eagles started their possessions on the Cowboy 44, 34 and 46, and in 2 of those 3 the defense held Philly to a FG. The Cowboy offense only had 52 yards the entire 1st half, so it didn't help at all.
The 2nd half the Cowboy defense was very good except on 1 Eagle possession. Other than one possession the Cowboy defense dominated.
Overall, 3 turnovers and a turnover on downs well into Cowboy territory is what lost the game. That's on the offense.