Against Philly, at least:
1) They hit on a couple of big plays. I think we're built well to stop the big plays, but stuff happens. A player can slip up mentally or physically one play, and that can be all the difference.
2) Their interior blitz kills us. We've done remarkably well about protecting Romo recently, but this has been one of the more disconcerting aspects about pass protection at times. Oh, and the Cole vs. Flozell matchup still worries me.
Honestly, those are the only things about them that scare me. They blitz the heck out of us and/or hit a few deep plays. I think we're playing very sound football right now.