I don't think a drastic change of philosophy is wise mid-season, especially with the current personnel. I do think there's something to the idea that the defensive scheme might be too complex, the coaches trying to constantly outhink their opponents rather than just lining up and winning the individual matchups. Try simplifying the scheme and letting the Cowboys athletes make plays. There does seem to be some validity to the idea that a lot of the big plays being given up are not because the Boys are being whipped at the point of attack, but that they're often out of position. If execution is the problem, streamline and let the players cut loose more. Overall, the defense has been decent, but with the secondary being thin due to injury and suspension, a more straightforward aggressive approach might work better. And just for my taste, I wouldn't mind seeing the corners switching up some and playing more press coverage. Henry and Jenkins are big, strong guys who would seem to be well suited to that approach. I've never liked seeing corners ten yards off wideouts.
But, for God's sake, the offensive line has to play MUCH better. They're supposed to be the strength of the team, but they're getting flat-out owned.