I've already reviewed the challenges that Seattle's offense will present the Eagles on Sunday. What about the Seahawks' defense? Even with an injury to one of their best players in defensive end Michael Bennett, the Seahawks boast one of the toughest defenses in the league. With Pro Bowl-quality players at every level, Pete Carroll's unit challenges offenses each week because of its personnel and quality of execution.

This is still a bit of a new look for Seattle's famed defense, which has been known for its simple, yet extremely effective, Cover 3 scheme with three deep defenders, four underneath and a four-man rush.

Shot 1 - The #Seahawks have long been a traditional Cover 3 team with a four-man rush underneath. Still a big part of their scheme pic.twitter.com/gdiFDrvzfR — Fran Duffy (@fduffy3) November 18, 2016

This is a simple interception for star cornerback Richard Sherman, but you see the defense at work. As Sheil Kapadia details in his awesome piece on Carroll's scheme, Seattle's zone coverage concepts has a basketball "matchup zone" kind of feel to it. Every defender has an assigned area and when opponents come into that area, it essentially becomes a man-to-man situation. With the same core group of defenders in the back seven, the communication in pass-off situations is often outstanding. On this play against Buffalo, you can see the advantages of zone coverage as Sherman drops back into his area in the deep third with his eyes on the throw, allowing him to capitalize on a miscommunication between the quarterback and the receiver.

This is what the Seahawks have been known for in the secondary for as long as Carroll has been there, regardless of who the defensive coordinator has been. Whether it was Gus Bradley, Dan Quinn or even last year with Kris Richard, that is the Legion of Boom's identity. But late in the 2015 season, you started to see a little more man coverage. Sherman, instead of staying on one side of the field, would travel with receivers across the formation. Instead of sticking with a basic four-man rush, offenses began to see more stunts and five-man pressure schemes with a mix of zone or man coverage behind it. This season, that has continued to an even greater extent. Cover 3 is still a big part of what the Seahawks do, but this team runs more man concepts than before now that Sherman has developed into one of the top cover corners in the NFL.

Shot 2 - This year I've seen much more man coverage though. Sherman is one of the best lockdown corners in the NFL #Seahawks pic.twitter.com/vWZpZY0rYw — Fran Duffy (@fduffy3) November 18, 2016

Here's two examples of Sherman in man coverage from this season, lining up in a place other than his typical left cornerback spot. First against Brandon Marshall in New York, you see him disrupt at the line of scrimmage as he does so well, get in phase with the receiver, turn to find the football and finish for the interception. In the second play against Arizona's John Brown, Sherman is in the slot, where he gets his hands on Brown early. He has his eyes on the quarterback to see the ball thrown, and he peels off of his man to lay a huge hit on Larry Fitzgerald on one of the Cardinals' "rub" concepts. This was a man coverage play, but the instincts that Sherman has shown as a zone defender came in handy, as did his ability to disrupt early in the down in a press coverage situation.

Shot 3 - Earl Thomas as the 'Robber' in man coverage is lethal. Instinctive, explosive, physical safety. One of the NFL's best #Seahawks pic.twitter.com/1ZiXYIebaU — Fran Duffy (@fduffy3) November 18, 2016

One of the Seahawks' favorite man coverage concepts this season has been Cover 1 Robber. The term robber comes from the safety who rolls down into the box as an underneath defender in the middle of the field taking away (or "robbing") routes in the intermediate area. We've seen strong safety Kam Chancellor in this role before, but free safety Earl Thomas has been that player for them a lot this year and he has really thrived in it. With his combination of instincts, toughness and short-area burst, Thomas patrols the middle of the field like a hawk (I should be put on timeout for that awful wording) and is a thorn in the side of opposing quarterbacks.

Here against Atlanta and Matt Ryan, Thomas is lined up shaded to the boundary side, really disguising what his role will be. At the snap, you see him drift toward the middle of the field as he breaks up this in-breaking route from Mohamed Sanu. Ryan never saw Thomas coming from the other side of the formation. With the amount of routes the Eagles run over the middle, it would not surprise me in the slightest to see this coverage from Seattle on Sunday.

Shot 4 - Thomas' instincts and range show up against the run and the pass. Has been playing at a high level this season #Seahawks pic.twitter.com/Vec9uj29XP — Fran Duffy (@fduffy3) November 18, 2016

Thomas' range and instincts make him such a dynamic player in Seattle's secondary. He's not a true "robber" on this first play against Atlanta in the clip above, but he's lined up to the boundary side again and you see him play the routes in the middle of the field. Watch as he feels both of these routes while maintaining vision on the quarterback, first feeling the tight end before seeing the throw and crashing down to disrupt the receiver on the shallow cross. In the run game, you see Thomas' ability to run the alley and come from great distance to wrap up one on one in the flats. Thomas is regarded as one of, if not the, top safeties in the NFL, and for good reason. He lives up to the billing.

One of the other big changes in Seattle is the Seahawks' propensity to send extra rushers at opposing quarterbacks. Sure, they sent their share of blitzes before, but now they send the heat at a much higher rate than previous seasons. What makes them even more effective is that they often blend their blitzes with defensive line stunts up front, adding to the confusion for offensive protection schemes.

Shot 5 - Something else that stands out watching #Seahawks this year, much more Stunts up front. T/E gets Avril free for sack on this play pic.twitter.com/GTBjerW5dT — Fran Duffy (@fduffy3) November 18, 2016

This is just your basic "TE Stunt" (T for tackle first, E for end second on the pressure), and it results in a sack for veteran defensive end Cliff Avril. It seems simple enough, as the defensive tackle slants outside to create interference for Avril as he loops inside the offensive guard on his way to the quarterback. The Seahawks had a large amount of success with these early in the season in large part because that was not a part of their DNA in recent years. Now, it's very common to see TEs, ET Stunts (where the defensive end penetrates before the tackle loops) and TT Stunts (where both tackles work off of each other) in their pressure schemes.

Shot 6 - Many of #Seahawks 29 sacks this year have come on blitzes combined with stunts up front. E/T and T/T stunts pivotal on these two pic.twitter.com/NnLbMZHyyi — Fran Duffy (@fduffy3) November 18, 2016

Here's an example of two sacks for the Seahawks where you see an extra blitzer come from the second level, but it's paired with a stunt up front. On the first play against Arizona on third-and-7, linebacker Bobby Wagner comes on a blitz but you get an ET Stunt that also creates penetration up front. Against Buffalo, the Seahawks pair a Cross Dog pressure with a TT Stunt with defensive ends Frank Clark and Damontre Moore for the sack. This is a big part of what Seattle does now in the trenches, and the Eagles' offensive line must be prepared for that part of the scheme.

Shot 7 - The player that must be blocked up front with M. Bennett out? Frank Clark. Wins inside & outside. Relentless pass rusher #Seahawks pic.twitter.com/tq25CaA59Q — Fran Duffy (@fduffy3) November 18, 2016

Like the rest of the Seattle defense, scheme is important, but you cannot forget about their personnel. On both of those pressures above you saw Clark, No. 55, doing damage to opponents. Last year's second-round pick out of Michigan is incredibly disruptive, and with Bennett on the shelf he is performing at a very high level. Like Bennett, Clark can line up outside at end or inside at tackle, where he is able to win against offensive guards. Everyone on the Eagles' offensive line must be aware of Clark, because he lines up at every technique along Seattle's defensive front.