In previewing an enemy opponent, a fun place to start is with their weaknesses. The Arizona Cardinals are known for having a bad offensive line. But how bad is it? The following rankings are courtesy of ProFootballFocus.

Overall: Pass blocking (31st), Run blocking (26th)

Cards starting offensive line from left to right:

Left Tackle: Bradley Sowell - 76th out of 78.

Left Guard: Daryn Colledge - 20th out of 74.

Center: Lyle Sendlein - 18th out of 34.

Right Guard: Paul Fanaika - 68th out of 74.

Right Tackle: Eric Winston - 70th out of 78.

This unit clearly isn't very impressive. The two tackles are among the worst rated in the NFL. Sendlein is a below average center. Right guard Paul Fanika, former Eagles seventh round draft pick, struggles at right guard. Daryn Colledge is their best ranked offensive lineman.

Meanwhile, the Eagles front seven has played well recently. Philadelphia managed to pressure Washington QB Robert Griffin III in their most recent match-up. The Eagles defense will aim to do the same when going up against veteran QB Carson Palmer.

The Eagles defensive line is the strength of their unit. Fletcher Cox and Cedric Thornton are two young productive 3-4 defensive ends. Thornton is a force against the run while Cox can push the pocket with pass rush ability. Rookie nose tackle Bennie Logan is coming off the best performance of his rookie career. Logan recorded five QB hurries against Washington. Second year defensive end Vinny Curry comes off the bench and provides pass rush as well. Plus, there's still the pass rushing linebackers (Trent Cole, Connor Barwin) for the Cardinals to worry about.

If the Eagles can be disruptive up front, it could make life tough on the Cardinals offense. Arizona has played well offensively in recent weeks but still rank 16th in yards per game and 18th in points per game. Football Outsiders lists the Cardinals offense at 25th overall in their offensive DVOA rankings. They've also turned the ball over the 7th most times.

The Cardinals have some skilled players on offense such as wide receivers Larry Fitzgerald and Michael Floyd, along with rookie runningback Andre Ellington (ruled questionable). Winning the battle in the trenches could go a long way towards neutralizing those threats and securing a fourth straight Eagles win.