When the Eagles matchup with the Bengals tonight, we'll see one bad team (the Eagles) take on a team that may very well be the absolute middle of the league. The Bengals are average, in nearly every way.
Let's take a look at the offense. Cincy ranks 15th in total yards, 13th through the air and 14th on the ground. Their QB, Andy Dalton, ranks 12th out of 26 QBs who have started all 13 games in terms of QB rating. He throws a lot of TDs (25) and is ranked in the top 5 in that category, but he's also throws a lot of picks, 14, which is also 5th most in the NFL. Benjarvus Green-Ellis is probably best described as an average RB.
The one area where they do have a true standout on offense is WR A.J. Green, who has almost 80 catches for over 1,100 yards and 10 TDs this season. His presence certainly inflates the numbers of Andy Dalton and changes the way teams approach defending them.
On defense, they're a little better. 7th in yards per game, 10th against the pass and 11th against the rush. However, if you rank by points allowed... They're right near the middle of the league in 15th.
If you look at their record, they're 7-6 and overall have beaten pretty much who you would expect. For several years they've been unable to beat their chief divisional rivals, Pittsburgh & Baltimore, and so far this season that hasn't changed. They've racked up wins against the Raiders, Chiefs, Browns, Jaguars & Chargers this season. They pretty much failed their real non-division tests against teams like Denver or Dallas.
The one real impressive win on their schedule was over the Giants in early November. The Giants were struggling at the time, but it's still a quality win. They also beat Washington early in the season before they really picked things up.
Last season was no different. They managed a 10-6 record without beating a single team with a winning record or that went to the playoffs.
So yeah, the Bengals are pretty much average. So as we watch tonight for signs of growth in Nick Foles, the young d-lineman, the offensive line, Bryce Brown... They're being measured against the NFL's midpoint. Do well against the Bengals, you might be better than average. Struggle and you're probably below average.