A cursory glance at PFF's defensive rankings will show that the Eagles are on of the best defenses in the league at this point. However, when you dig deeper, there are some pretty big flaws that can be exploited by good offenses mainly: pass coverage.
Now, I know most of you cringed when you read the term "good offenses", because Tennessee doesn't have one of those, but there is an exception to this. When Mettenberger got into rhythm with Delanie Walker against the Baltimore Ravens, this Titans team looked like it finally had an offense that could put up some points. We all know what happened next, but the point remains that Mettenberger is progressing and now that he has the momentum of a good game combined with getting his best receiver back, this might be a sneaky good game for him.
A great pass rush masks a bad back seven, and if Walker gets one-on-one coverage with Bradley Fletcher, Connor Barwin, Casey Matthews, or Nate Allen then he get tear the Eagles up.
The Titans need Mettenberger to be decisive and hit his back foot ready to through the ball. If he takes too long, someone from this good Eagles defense is going to beat one of the four bad offensive linemen of the Titans.