The league's defensive front-seven units are easily one of the most difficult groups to rank in the NFL. With other positional groups, analysts have to consider one or two aspects of the game at most, but with the front-seven, pass-rushing, run defense, and the coverage prowess of linebackers all have to be factored in.

To arrive at this season-ending ranking, we leaned on our season grading of the starters, with strong deference to those receiving the bulk of the snaps. When injuries occurred, we weighed the snap counts of the injured players against his replacement in order to arrive at the most accurate ranking.

1. Seattle Seahawks

Top overall grade: LB Bobby Wagner, 90.9

Lowest overall grade: NT Jarran Reed, 44.2

The class of the league for some time, the Seahawks paired the league’s most productive linebacker duo this season with a defensive line that can get pressure via multiple avenues. Cliff Avril, Michael Bennett, and Frank Clark all had top-40 pass-rushing grades among edge players, while Bobby Wagner and K.J. Wright both finished with top-10 grades for off-ball linebackers.

2. Philadelphia Eagles

Top overall grade: DE Brandon Graham, 93.3

Lowest overall grade: DE Connor Barwin, 42.1

It was a difficult decision between the Eagles and the Seahawks for the No. 1 spot, as this front-seven propped up a hodge-podge secondary to form one of the league’s most effective defenses for a good portion of the season. Brandon Graham and Fletcher Cox finished with the third- and fourth-highest pass-rushing productivity marks at their respective positions. Philadelphia's front-seven also features a budding star in second-year linebacker Jordan Hicks, who led all players at the position with five interceptions.

This is PFF's 2016 All-Pro Teamhttps://t.co/3WcaYpoxkX including Eagles DE Brandon Graham pic.twitter.com/Q8sLOjjc1j — PFF (@PFF) January 5, 2017

3. Carolina Panthers

Top overall grade: DT Kawann Short, 87.7

Lowest overall grade: NT Star Lotulelei, 46.9

Carolina started off slowly, but by the middle of the season, the Panthers were once again dominating around the line of scrimmage. Everyone knows about Kawann Short by now, who finished as the third-highest graded interior defensive lineman, but defensive end Mario Addison’s season flew more under the radar. He finished fourth among all edge players in pass-rushing productivity and racked up his double-digit sack total in only 433 snaps all season.

4. Los Angeles Rams

Top overall grade: DT Aaron Donald, 95.6

Lowest overall grade: DE Robert Quinn, 60.6

Aaron Donald on his own would be good enough to beat out a handful of front-sevens around the league, but pair him up with a myriad of other talented pass-rushers and you get a top-five unit. Defensive end William Hayes and defensive tackle Michael Brockers both earned top-25 grades at their respective positions in 2016. The play, when healthy, from defensive end Robert Quinn, though, is mildly concerning. His pass-rushing productivity has declined every year since 2013.

5. Arizona Cardinals

Top overall grade: DE Calais Campbell, 90.4

Lowest overall grade: DT Corey Peters, 73.8

The Cardinals' defense finally got something they’d been missing for some time—an edge rush. Unfortunately, it just so happened to coincide with the collapse of their secondary. Chandler Jones had a career year, finishing with the seventh-highest grade of any edge player, while Markus Golden made the second-year leap, finishing 24th. As a whole, Arizona recorded the highest pressure rate of any team in the NFL, at 40.15 percent.

6. Minnesota Vikings

Top overall grade: DT Linval Joseph, 83.3

Lowest overall grade: LB Anthony Barr, 43.1

It’s amazing that the Vikings are among the top 10 on this list with Sharrif Floyd playing only 25 snaps all season long and Anthony Barr disappearing for long stretches of play. Helping quell those losses, though, were the performances of second-year players Danielle Hunter and Eric Kendricks. Hunter was 15th among edge players in pass-rushing productivity, while Kendricks was seventh among inside linebackers in run-stop percentage.

7. Denver Broncos

Top overall grade: OLB Von Miller, 91.1

Lowest overall grade: DE Jared Crick, 41.3

For much of the season, this team felt like “Broncos-lite” compared to a year ago. It seemed like they should have been relatively the same unit, but you just couldn’t quite put your finger on why things were different. The fact of the matter is that losing studs like Malik Jackson and Danny Trevathan had a ripple effect that saw this unit take a step back as a whole. Even though they still got pressure on opposing quarterbacks at the second-highest rate in the NFL, they had to blitz at the third-highest rate to do so. The Broncos' run defense suffered, as well, with Sylvester Williams and Jared Crick grading out among the worst interior players in that regard.

8. Kansas City Chiefs

Top overall grade: DE Chris Jones, 83.5

Lowest overall grade: NT Dontari Poe, 55.8

This was one of the most difficult units to rank. If everyone was fully healthy all season long, the Chiefs could very well have been No. 1. But that wasn’t the case, and multiple players seemed to play through nagging injuries, limiting their production. Jaye Howard, Dee Ford, Derrick Johnson, and Justin Houston all missed time at some point during the year, while Ford and Houston had multiple games where they actually played hampered by injury. It was still a quality unit, though, with the play of rookie defensive tackle Chris Jones being a revelation. The second-rounder finished with the fifth-highest pass-rushing productivity mark among interior players.

9. Green Bay Packers

Top overall grade: DE Mike Daniels, 85.3

Lowest overall grade: OLB Clay Matthews, 44.6

The Packers' defense has been hounded for their incompetency all season long, but those struggles almost entirely reside in the secondary. In fact, almost every player the Packers threw out along the defensive line performed at an above-average level—Datone Jones, Julius Peppers, Mike Daniels, Kenny Clark, Letroy Guion, and Nick Perry all fit that bill. The only thing holding Green Bay back is the lack of an impact linebacker, as the team's highest-graded player at the position, Jake Ryan, was still only 43rd overall.

10. Houston Texans

Top overall grade: OLB Whitney Mercilus, 87.4

Lowest overall grade: NT Vince Wilfork, 45.1

It's impressive to see that, without the best defensive player of the last decade, the Texans still fielded a top-10 front-seven this year. Jadeveon Clowney continued the dominant level of run defense he flashed in 2015, while Whitney Mercilus firmly established himself as one of the league’s premier edge rushers. It’s a shame, though, that injury has zapped Brian Cushing of his dominant blitzing prowess, as he managed three combined sacks and hits this year after averaging 13 over his first three season in the league.

11. New York Giants

Top overall grade: DE Jason Pierre-Paul, 86.2

Lowest overall grade: LB Keenan Robinson, 44.0

As far as a run-stuffing defensive lines goes, there wasn’t a better unit than the Giants in 2016. Damon Harrison is in a league of his own when it comes to nose tackles, leading the NFL in run-stop percentage for the fourth-straight season. Unfortunately for the D-line, the linebackers didn’t hold up their end of the deal. Kelvin Sheppard finished with the lowest run-stop percentage of any NFL linebacker this season.

12. Miami Dolphins

Top overall grade: DT Ndamukong Suh, 87.2

Lowest overall grade: DE Andre Branch, 56.4

Few teams recorded pressure with four-down linemen quite like the Dolphins in 2016. They pressured quarterbacks on 38.4 percent of their dropbacks, the fourth-best rate in the league, even though they were 22nd in blitz rate. That didn’t look like it would be the case after Cameron Wake’s 2015 season ended with a torn Achilles, however. His comeback was nothing short of miraculous, as even at 34 years old, he played as if he never got hurt in the first place. His 14.1 pass-rushing productivity mark was third-best in the NFL.

13. Tennessee Titans

Top overall grade: DE Jurrell Casey, 85.4

Lowest overall grade: LB Avery Williamson, 76.5

Dick LeBeau brought his aggressive style of defense to the Titans this year, and while they may not have had the talent to make it work on the back end, the front-seven did its part. The Titans pressured opposing quarterbacks at the eighth-highest rate in the NFL, and saw Jurrell Casey, Karl Klug, Brian Orakpo, and Derrick Morgan all finish with top-30 pass-rushing grades at their respective positions.

14. San Diego Chargers

Top overall grade: DE Joey Bosa, 89.9

Lowest overall grade: DE Corey Liuget, 49.3

No team in the NFL had a more productive edge duo than Joey Bosa and Melvin Ingram this past year, as they finished fifth and sixth, respectively, at the position. Outside of that pair, however, there was not much to speak of whatsoever. Nose tackle Brandon Mebane had a career resurgence, but only managed 340 snaps, as he was lost for the season in Week 10. Corey Liuget didn’t manage a sack all season on 495 pass rushes, the most for any such player in the NFL.

15. Oakland Raiders

Top overall grade: OLB Khalil Mack, 93.9

Lowest overall grade: DE Jihad Ward, 37.7

Much like Aaron Donald with Los Angeles, Khalil Mack can carry a front-seven all on his own. The Raiders, though, gave him considerably less help the Rams gave Donald. The interior, in particular, was a sieve. Rookie second-round pick Jihad Ward was simply not ready for the rigors of the NFL, and finished as the lowest-graded starting interior lineman. Even more disappointing was the season from nose tackle Dan Williams, who was dominant in 2015 with a 12.1 run-stop percentage, but then saw that plummet to only 4.9 percent this season.

16. Pittsburgh Steelers

Top overall grade: OLB James Harrison, 86.7

Lowest overall grade: LB Lawrence Timmons, 46.4

If one could summarize the Steelers' front-seven in two words, they would be: missed tackles. They have the talent to play much better than the 16th-best front-seven any given week, but they struggle mightily finishing plays at times. Ryan Shazier’s 21 missed tackles were the fourth-most among linebackers, while Stephon Tuitt’s ridiculous 12 missed tackles were the most of any interior defensive lineman. It’s amazing to think that their most productive player is still 38-year-old James Harrison, a player whom it appeared they’d moved on from four years prior when he was cut and left free to sign with the divisional-rival Bengals..

17. Baltimore Ravens

Top overall grade: LB C.J. Mosley, 85.8

Lowest overall grade: LB Zachary Orr, 42.7

Arguably the best run-stuffing front-seven in football, the Ravens almost stuffed the run to their detriment at times. Michael Pierce, Timmy Jernigan, Lawrence Guy, and Brandon Williams all earned top-25 run-defense grades among interior players, but none finished in the top 50 for pass-rushing grades. They would finish 29th overall in pressure rate.

18. New England Patriots

Top overall grade: LB Dont’a Hightower, 85.4

Lowest overall grade: OLB Rob Ninkovich, 49.8

The Patriots, much like the Ravens before them, were a run-stopping unit first and foremost. Alan Branch, Malcom Brown, and Trey Flowers were all dominant this year against the run; Branch and Brown finished second and third among all defensive tackles in run-stop percentage, while Flowers finished 10th among edge players. Unfortunately, they too had their struggles getting after the quarterback, as the Patriots were 24th in team pass-rushing grade.

19. Cincinnati Bengals

Top overall grade: LB Vontaze Burfict, 87.6

Lowest overall grade: DE Michael Johnson, 41.1

The talent disparity along the Bengals' defensive line is quite amazing. Geno Atkins and Carlos Dunlap are both top-15 players at their respective positions, but the line didn’t feature a single other player with a competent grade in 2016. Michael Johnson, Domata Peko, Pat Sims, and Will Clarke all saw more than 350 snaps, with none of them grading higher than 46.6.

20. Buffalo Bills

Top overall grade: LB Zach Brown, 84.1

Lowest overall grade: LB Preston Brown, 49.8

The Bills' talent is likely better than 20th-best in the NFL, but it didn’t play beyond that level this season. Buffalo finished eighth in total sacks, though that doesn’t reflect the team's true ability to impact opposing quarterbacks down after down. They were 23rd in pressure rate on opposing quarterbacks, with guys like Kyle Williams and Marcell Dareus having down years in that regard. They were also routinely gashed by wide runs, and had some of the poorest gap discipline of any team in the league this year.

21. Washington Redskins

Top overall grade: LB Mason Foster, 86.3

Lowest overall grade: DE Ziggy Hood, 41.7

Why the Redskins chose to part ways with Stephen Paea in order to give Ziggy Hood 662 snaps, I have no idea, but it certainly didn’t work out for them. Hood earned the fourth-lowest run-defense grade of any starting interior lineman this year, and collected only 17 QB pressures all season long. The weak interior ruined what were very impressive seasons from their outside linebackers, Ryan Kerrigan and Trent Murphy, who both totaled over 20 combined sacks and hits.

22. Dallas Cowboys

Top overall grade: LB Sean Lee, 88.0

Lowest overall grade: DT Maliek Collins, 39.6

Despite all of Dallas’ success this season, the fact of the matter is that they struggled to pressure opposing quarterbacks. They were second to last in pressure rate, despite facing a good deal of obvious end-of-game passing situations. Their ranking here—and often times their run defense—is salvaged by one Sean Lee. The linebacker was dominant at times, serving as a one-man defense against Washington in Week 12 and the Giants in Week 14.

23. Chicago Bears

Top overall grade: LB Jerrell Freeman, 93.8

Lowest overall grade: OLB Sam Acho, 44.7

One of the most impressive pure statistics any player amassed this season came from Bears linebacker Jerrell Freeman. He made 40 tackles in coverage while missing only one tackle attempt. That ratio is insane, and it’s the best we’ve recorded since 2012. That’s about the only exciting stat, though, as the Bears' front-seven desperately missed a fully-healthy Pernell McPhee for a good portion of the year.

24. Atlanta Falcons

Top overall grade: LB Deion Jones, 79.3

Lowest overall grade: LB De’Vondre Campbell, 57.6

The Falcons were lucky that their offense was able to often build early leads, because this run defense was mostly smoke and mirrors in many games. Atlanta didn’t have a single player that you could point to and say, “He’s good against the run.” Nose tackle Grady Jarrett earned the unit's highest grade in run defense, and even he was only 52nd in that regard among interior defenders. Saving this unit from the bottom five was the breakout of second-year sack artist Vic Beasley, who led the NFL with 16 sacks.

25. Tampa Bay Buccaneers

Top overall grade: DT Gerald McCoy, 85.2

Lowest overall grade: NT Clinton McDonald, 40.6

The amount of holes that the Bucs continue to field along their defensive line is staggering. Robert Ayers made up for that a bit, with 25 combined sacks and hits on the year, but they still were forced to give Davonte Lambert 374 snaps—in return he repaid them with one total pressure all year long. Tampa Bay's linebacker duo of Kwon Alexander and Lavonte David, while good in coverage, missed a combined 36 tackles this season, third-most of any duo.

26. Jacksonville Jaguars

Top overall grade: LB Paul Posluszny, 88.4

Lowest overall grade: DE Yannick Ngakoue, 41.3

No team struggled to create pressure off the edge more than the Jaguars. As a team, they were 25th in pressure rate, but their starting ends, Yannick Ngakoue and Dante Fowler, were 44th and 48th in pass-rushing productivity, respectively, among starters. The only saving grace was the linebacker corps. Paul Posluszny led all linebackers with 23 stops in coverage, while Telvin Smith wasn’t far behind, with 21.

27. New York Jets

Top overall grade: DE Leonard Williams, 85.1

Lowest overall grade: LB Darron Lee, 38.3

A unit with so much promise, the Jets' defensive front-seven absolutely fell to pieces in 2016. Muhammad Wilkerson was a shell of his former self, playing so poorly that his five-year, $86 million contract looks terrifying on the ledge at this point. He made PFF’s top 101 players each of the past two seasons, but could only manage a 44.1 grade this year. New York blitzed at the third-highest rate of any team in the NFL, yet only managed the 20th-best pressure rate.

28. New Orleans Saints

Top overall grade: DE Cameron Jordan, 92.1

Lowest overall grade: LB Craig Robertson, 51.2

This Saints' defensive line featured one of PFF’s All-Pro second team defensive ends, but that’s it. Nick Fairley was the second-highest-graded player in the unit, but even he comes in at 76.9. The fact is that, outside of Cameron Jordan’s ridiculous 79 pressures on 619 pass rushes, the rest of the New Orleans defense managed 170 total QB pressures on 2,202 pass rushes. That’s awful, considering that the Saints blitzed more than any other team in the NFL (41.3 percent of snaps).

29. Cleveland Browns

Top overall grade: NT Danny Shelton, 82.4

Lowest overall grade: DT Jamie Meder, 42.8

This ranking was to be expected when relying on a handful of rookies to play impactful snaps up front. What wasn’t as expected was the general ineffectiveness of Jamie Collins after coming over from New England. During his eight games with the Browns, Collins surrendered 27 catches on 30 targets for 235 yards and two touchdowns without getting his hand on a single pass.

30. Detroit Lions

Top overall grade: DE Kerry Hyder, 78.2

Lowest overall grade: LB Tahir Whitehead, 37.6

With Ziggy Ansah hampered for most of the year with an injury and Haloti Ngata slowing down considerably in his early 30s, the Lions were often dominated up front. This was a unit that featured the lowest-graded starting edge player in the NFL (Devin Taylor), as well as the lowest-graded starting linebacker (Tahir Whitehead).

31. San Francisco 49ers

Top overall grade: LB Gerald Hodgers, 82.4

Lowest overall grade: LB Michael Wilhoite, 38.5

The 49ers fielded one of the worst run defenses of all-time this season, allowing almost 400 more yards on the ground than any other team. They didn’t have a single player along the defensive line that could effectively hold up to double teams, and the stunts and games they ran to try and counter that only left them more susceptible to big plays. In almost any other season, they’d easily have been ranked dead last.

32. Indianapolis Colts

Top overall grade: LB Edwin Jackson, 61.6

Lowest overall grade: OLB Erik Walden, 41.2

The grades above speak for themselves. Two other teams this year had their worst starter in the front-seven grade out better than the Colts' best starter. Indianapolis pressured opposing quarterbacks on a comically-low 25.4 percent of their dropbacks, despite blitzing at a higher rate than the league average.

Want more 2016 season grades? Access Pro Football Focus' Player Grades tool now to see season marks for every player, as well as position-specific rankings and game-by-game snap counts.