When you prepare for the New England Patriots' defense, there are a lot of factors that come into play.

This is a unit that cycles in a ton of different personnel groupings. They're extremely multiple with their fronts, lining up in a wide variety of alignments with four, three, and two down linemen. Not only do they have at least two distinctly different nickel packages with five defensive backs, but they also have multiple dime groups (with six DBs) and even "dollar" subpackages (with seven DBs). Their linebackers all have a responsibility. Their defensive linemen line up everywhere and all play a role. If you're active on gameday for Bill Belichick, you're going to see snaps and be a part of the weekly plan of attack.

Let's start up front with the defensive line, where two players, in particular, have really stood out to me during my film study of this unit.

Note that there is audio commentary for each of the video clips.

Shot 1 - In my opinion the most disruptive player on the #Patriots front line is DE Trey Flowers. Literally lines up everywhere along the line of scrimmage and wins with his heavy hands and LONG frame. Will be a big test on Sunday night. pic.twitter.com/0H2YZfYyRZ — Fran Duffy (@fduffy3) January 30, 2018

Shot 2 - Former 1st Round Pick DT Malcom Brown is very disruptive for the #Patriots as well. Has had to play a lot of nose this year and is still performing at a high level. Can both 2-gap and 1-gap for this defense. #Eagles have to account for he and Flowers on Sunday night pic.twitter.com/z2yhlIn249 — Fran Duffy (@fduffy3) January 30, 2018

Both Trey Flowers and Malcom Brown line up in a number of alignments and find ways to win, just in different ways. Flowers, who boasts an 84.5-inch wingspan (the longest of any edge rusher drafted in the last decade, by my records), wins with length and leverage. He's not an explosive pass rusher off the edge, but if he gets into your pads he can lock out his arms and drive you back into the quarterback or own you at the point of attack in the run game. He'll line up against Halapoulivaati Vaitai for a majority of the time, most likely, but he also gets snaps over guards and on top of the center, so this is an assignment for the entire offensive line.

The same could be said, though to a lesser extent, for Brown, who spends most of his time on the inside. Both guards, Brandon Brooks and Stefen Wisniewski, as well as center Jason Kelce, will need to be very familiar with his scouting report. The former first-round pick out of Texas wins with leverage and natural pad level off the ball, and he's had to play a whole lot of snaps at nose tackle due to injuries along that front this year. He's very similar to Atlanta's Grady Jarrett, who the Eagles faced back in the Divisional Round and is one of the most disruptive players at his position in the entire NFL.

Other players the Eagles need to watch for include veteran Lawrence Guy, who lines up both inside and outside depending on the front. Ricky Jean-Francois is a very disruptive run defender who has heavy hands and can dominate at the point of attack if he's given the chance. He's a stout player who uses his hands very well. Eric Lee, a subpackage player off the edge, is often used with all of their stunts and twists when they get into nickel and dime.

What was fascinating to me when watching this defensive front was its multiplicity. On any given play, the Patriots may come out in base personnel in a 4-3 front. On the next play, they may come out in their "big nickel," but line up in a 3-4 front with the slot player, Patrick Chung, lined up as a stacked linebacker in the middle of the defense. After that, they may go back to base but line up in a straight 3-4 alignment.

There are so many different combinations of packages and then alignments, so as an offensive line (and an offensive unit in general), you have to be prepared for every member of the defense. For instance, if you're Vaitai, on any given play you may see Jean-Francois, Flowers, Lee, Kyle Van Noy, James Harrison, Deatrich Wise, Chung, or any of their defensive backs on the blitz (we'll get to that later), and they may be coming at you as a 5-, 7- or 9-technique, or even on a stunt. That makes this game a major "tape study" week for the offensive line.

In the playoffs, in particular, there was one other tendency that I saw from this unit, and it happened very late in the pre-snap phase of the down. It's something I'm sure the Eagles are prepping for with the extra week of film work.

Shot 3 - Something else I saw a lot from the #Patriots defense, particularly in the playoffs, is that they'll do a late shift up front just before the snap, typically from a 4-3 into more of a 3-down or 'Bear' look. Multiple positive effects in the run game #Eagles pic.twitter.com/ZbjMKJnvwA — Fran Duffy (@fduffy3) January 30, 2018

When you see late shifts right before the snap, it can do a lot to change things from a blocking assignment perspective. So a young and inexperienced offensive line may struggle to react to those adjustments on the fly, especially on such a big stage. The other aspect of this, however, is the shift to a "Bear" front. Any time you see the three interior linemen (the guards and center) "covered up" (meaning they have defenders lined up over them), it's very hard to get double teams going in the run game. With the Eagles' zone run game so reliant on double teams, it wouldn't shock me to see a lot of "Bear" looks from the Patriots on Sunday night.

From a pressure standpoint, Belichick and defensive coordinator Matt Patricia like to mix things up. Some games you'll see a lot of blitzing, and in others, you'll see them back off a bit and rely on the four-man rush. How they will play it on Sunday remains to be seen, but here are some examples of what you may see the Patriots run against the Eagles.

Shot 4 - Here a couple of examples of what the #Patriots will do with their pressure schemes. They will mix things up with who comes, but there's one consistent theme that I saw on a near-weekly basis from this unit, which I'll get to on the next shot. #SuperBowl #Eagles pic.twitter.com/oFYEO0bVxt — Fran Duffy (@fduffy3) January 30, 2018

There are a lot of different things they do from a pressure standpoint, but the one staple that I've seen from New England on a near-weekly basis is the use of defensive backs in their blitz packages. New England loves to play the game in its subpackages, and when they line up with extra defensive backs on the field they love to send them at the quarterback from different depths and angles. Here are some examples of how they do it.

Shot 5 - If the #Patriots are blitzing, it's going to be out of their Dime (6 DB) and Dollar (7 DB) subpackages. They love sending DBs after the quarterback, and they'll double cover the WR in the void for good measure. Extremely effective tactic for them on passing downs pic.twitter.com/WA7fqEQPU0 — Fran Duffy (@fduffy3) January 30, 2018

Typically, when you see a cornerback or a safety blitzing off the edge, a quarterback's first instinct is to throw it "into the blitz," right at the receiver that was previously covered by the blitzer before the snap of the ball. The Patriots counter that by double teaming that receiver with two defenders, typically a safety playing with outside leverage and a linebacker playing inside leverage flying from the middle of the field. They do a very good job of disguising their blitzes as well, making them tough to recognize before the snap. Even when they are tipped, the defense does a good job of flowing to the football with good angles to stop the receivers short of the sticks.

If you want a quick way to recognize whether or not the Patriots are in their subpackages and a blitz could be coming, look right over the middle of the offensive line. If you see defensive tackle Adam Butler, a rookie from Vanderbilt, in the game, the Pats are likely in "Dime" or "Dollar." The only other real cue you can get is watching the alignment of the secondary.

If you see a safety lined up outside of a slot receiver (shaded closer to the sideline), with the slot corner lined up slightly inside of the receiver (closer to the quarterback), that's an instant clue that pressure is coming from that side. New England is pretty good at disguising it, but at times it'll tip its hand a bit. It will be up to Nick Foles, Doug Pederson, and the rest of the Eagles' offense to make sure they "burn the blitz" in this game, getting the ball out quickly in space to pick up positive yardage.

The Patriots don't only use those double teams in coverage on blitzes. They'll use a four-man rush and dedicate extra resources to take away key pass catchers on critical downs as well. When the Eagles are facing third down or are in the red zone, you can expect to see double-team concepts against some of the biggest names on the Eagles' offense - Zach Ertz and Alshon Jeffery.

Shot 6 - What does it mean when people say Bill Belichick tries to take away what an offense does best? Here are a few examples from this year. #Patriots #Eagles #SuperBowl pic.twitter.com/yXodQ455n7 — Fran Duffy (@fduffy3) January 30, 2018

The Patriots will use these double coverages everywhere on the field. So how do the Eagles attack it? Well, there are a few ways. First off, the receivers away from the double teams MUST win their one-on-one matchups. If Nelson Agholor is one-on-one, he has to win. Ditto Torrey Smith or Trey Burton or Mack Hollins or Brent Celek. Those guys have to find ways to win. Beating double coverage as a receiver often requires some kind of double move or just pure raw speed, so if the Eagles hit a situation where they think Ertz or Jeffery is going to get doubled, they may call a play that can attack that double team. The other way, and we saw the Steelers try to do this in the clip above, is to line up in a bunch formation.

This creates a lot of traffic for defensive backs to navigate through and gets them picked off (legally, of course). The Patriots gave up some big plays early in the season against teams like Carolina and Kansas City on plays out of bunch sets or using switch releases where defensive backs had to pass off assignments mid-play. They've tightened things up since then, but that's a way to attack that kind of man coverage scheme.

Shot 7 - The #Patriots are primarily a man coverage outfit, and their two outside corners, Stephon Gilmore and Malcolm Butler, allow them to play that way. Instinctive players with VERY good ballskills #Eagles #SuperBowl pic.twitter.com/qkUCOO8LgZ — Fran Duffy (@fduffy3) January 30, 2018

The reason why the Patriots can play so much man coverage (they play a lot of Cover 1 and Cover 2 man, one of my favorite coverages in football) is because of their corners on the outside. Stephon Gilmore and Malcolm Butler form a really good duo. Gilmore has been used to shadow bigger receivers this season, so I'd imagine he will be matched up early and often with Jeffery in this game. How Butler is used will be interesting. He'll see some of Smith, and perhaps some of Agholor as well. With his smaller frame, the Patriots don't really want to get Butler on Jeffery for too many reps one-on-one.

I mentioned that the Patriots have two "nickel" packages (with five defensive backs). They have a "regular" nickel, with former Eagle Eric Rowe coming onto the field. Rowe will play both inside and outside depending on the matchup, and he'll likely get reps against both Smith and Agholor on Sunday night. In their "big" nickel package, another former Eagle in Patrick Chung slides down into the slot from his strong safety spot. This allows young veteran Duron Harmon to come off the bench and slide into the safety position next to Devin McCourty, a dynamic player on the back end. Eagles fans don't have very fond memories of Chung during his time here, but he's been a dynamic player in that scheme because of his versatility.

Shot 8 - Another reason why the #Patriots are as effective as they are in the secondary is the play of S Patrick Chung. He will likely be matched up with TE Zach Ertz for most of this game, creating one of the biggest matchups to watch in Sunday's #SuperBowl #FlyEaglesFly pic.twitter.com/oz9bH4RBnc — Fran Duffy (@fduffy3) January 30, 2018

Chung is their primary man-to-man player in coverage against tight ends. He'll most likely be matched up with Ertz in this game. He'll also play close to the line of scrimmage both off the edge and inside from a "stacked" position. He is also used as a blitzer as well. When the Patriots go to "Dime," Chung goes into the slot along with Rowe, with Harmon rotating in at safety. Their seventh defensive back, former second-round pick Jordan Richards, is a smart, versatile player who comes on the field in their "Dollar" packages to match up with running backs and smaller tight ends.

As you can see, there are a ton of different combinations with personnel groupings and alignments with this defense. There's a lot to prepare for, and you can be sure that the Eagles' offense is working hard to get ready for it, even during the madness of Super Bowl week. It will be a fascinating chess match between Pederson and Belichick on Sunday night.