The 2012 regular season's top 10 defenses will feature some of the usual suspects, including two bitter AFC North rivals defined by their defensive excellence. However, there will also be be a few surprise names in the ranking, including an underrated NFC West group that is quietly developing into an elite unit.
A defense at the centre of the offseason's biggest scandal will benefit from the presence of a creative new coordinator and some key personnel additions. They will shock the league with their performance, and another man who many consider a failure as a head coach will leave no doubts about his skill as a coordinator.
The following units will make up the top 10 defenses for the 2012 season. They are presented in ascending order.
It's appropriate to begin the list with easily its most controversial entrant. The shame of the Bountygate scandal has distracted from the fact that the New Orleans Saints have made some excellent additions to a weak defense.
Bringing in Steve Spagnuolo to coordinate the group is the key upgrade. Spagnuolo runs an innovative and daring scheme. His fire-zone concepts will make the Saints less predictable than they were under the nefarious Gregg Williams.
Versatile young defensive linemen like second-year pro Cameron Jordan and rookie Akiem Hicks could thrive in Spagnuolo's system. They have the versatility and athleticism to act as zone-droppers and rush from multiple positions and stances.
However, it is free agency where the Saints have done the most to ensure a defensive improvement.
Brodrick Bunkley gives them a true 4-3 defensive tackle and will become the focal point of the run defense. Curtis Lofton is one of the best young middle linebackers in the game, and David Hawthorne has the blitz skills Spagnuolo can use in a variety of ways.
Having Dave Wannstedt call the plays will make a huge difference to the Buffalo Bills defense. Although he endured a mixed career as a head coach, Wannstedt has always been an outstanding coordinator. Wannstedt is a 4-3 master, and the Bills have given him all the pieces to create a fearsome unit from day one.
Free agency yielded Mario Williams and Mark Anderson, giving Buffalo bookend pass-rushers. The Bills also drafted ball hawk Stephon Gilmore. However, it is the defensive tackle tandem of Marcell Dareus and Kyle Williams that will make Buffalo's defense feared this season.
Dareus enjoyed a stellar rookie campaign, and his ability to occupy blockers and push the pocket will be huge assets in Wannstedt's scheme. If Williams can rebound from injury and recapture his 2010 form, the Bills will have arguably the best one-two interior combination in the league.
Wannstedt has often deployed 2-gap tackles, dating back to his days with the Miami Dolphins and the partnership of Tim Bowens and Daryl Gardener. Dareus and Williams will create one-on-one rush opportunities for Anderson and Mario Williams and open clear lanes of pursuit for speedy linebackers Nick Barnett and Kyle Sheppard.
The Philadelphia Eagles' pass rush will simply be too much for opponents to handle this season. Cullen Jenkins, Trent Cole and Jason Babin will continue to terrorise quarterbacks in the Eagles' daring line schemes.
The trio has been joined by dynamic rookie Fletcher Cox, who will make an immediate impact under the tutelage of legendary line guru Jim Washburn. The additions of DeMeco Ryans and rookie Mychal Kendricks at linebacker give Philadelphia even more license to turn their rampaging front four loose.
That's a frightening thought for the teams in Philadelphia's path, which includes the likes of the Cleveland Browns and Arizona Cardinals, two teams with major questions along the offensive line.
The addition of veteran free safety O.J. Atogwe shouldn't be underestimated either. The 30-year-old is a natural ball hawk who will protect the deep middle. The combination of relentless pressure up front and tight man coverage from corners Nnamdi Asomugha and Dominique Rodgers-Cromartie will overwhelm offenses throughout the season.
The Kansas City Chiefs defense is ready to take a step up and join the ranks of the league's best units. New head coach Romeo Crennel will still play a big role in running the scheme, and the Chiefs have a veteran and capable coaching staff directing a group of rising young stars.
As one of the few teams who still run a traditional 2-gap 3-4, the Chiefs rely on the play of their linebackers. They have an outstanding trio in Tamba Hali, Justin Houston and Derrick Johnson.
Hali and Houston are a potent edge-rushing duo, and the former is a match for any offensive tackle in the game. Johnson is a cerebral and active inside linebacker who is coming off his best season.
The Chiefs need top rookie Dontari Poe to quickly prove he can man the middle. If the ex-Memphis star can give the Chiefs a dominant 2-gapper at nose tackle, they will have one of the stronger front sevens in the NFL.
In the secondary, a smart, savvy group led by youthful ace Brandon Flowers will be boosted by the return of safety Eric Berry.
The Chiefs face a difficult schedule, including two meetings with Peyton Manning. They have plenty of defensive talent, though, so Crennel's scheming will be a deciding factor in big games.
The Seattle Seahawks defense can be one of the big surprises of the 2012 regular season. They have a powerful front seven and plenty of developing young talent in the secondary. Pete Carroll's expertise has always been on the defensive side of the ball, and he now has the pieces to make his attacking, hybrid schemes work.
It starts up front, where the Seahawks have one of the league's better defensive lines. Alan Branch and Brandon Mebane are formidable inside, and when the mighty Red Bryant is added to the mix, the Seahawks can repel any running game. Former Tennessee Titans standout Jason Jones was a good free-agent pickup, as he gives the rotation a true interior pass-rusher.
Chris Clemons plays the key "Leo" role, and Carroll wisely drafted his heir apparent in Bruce Irvin. Expect plenty of pressure from this duo.
Safety Earl Thomas is the fulcrum of a youthful and extremely aggressive secondary.
Brandon Browner and Richard Sherman combined for 10 interceptions in 2011. Both are physical enough to play the kind of press coverage that allows Carroll to blitz and attack offenses in waves this season.
The Baltimore Ravens lost some key personnel in free agency and will certainly miss the impact Terrell Suggs can create. However, they can still rely on Ray Lewis, Haloti Ngata and Ed Reed to maintain the team's place amongst the league's toughest defenses.
In the absence of Suggs, the defensive line can carry the unit. Pernell McPhee, Ryan McBean, Terrence Cody and Maake Kemoeatu will keep the group stout against the run.
Ngata remains the key, though. He has refined his technique and expanded his repertoire of pass-rush moves during the past two years and can become a regular playmaker behind the line of scrimmage this season.
Reed and Lewis may be nearing the end, but the motivation of one last run at a Super Bowl will push them to again produce fine individual seasons.
The New York Jets are still loaded with talent defensively, and Rex Ryan will learn from the mistakes of 2011 and return his unit to the ranks of the NFL's best.
Ryan has shown a willingness to adapt his system and play-calling while in New York. He reined in his heavy blitz approach in favour of a blanket coverage system to outwit Tom Brady in the 2010-11 AFC Divisional Round.
This season, Ryan has opted to reduce the number of 3-4 looks and include more 4-3 alignments, according to NFL.com. That's a smart move for a group which lacks a dominant edge-rusher but has plenty of size and talent up front.
Muhammad Wilkerson and Sione Pouha will be tough to move in the middle, and versatile rookie Quinton Coples should be a pass-rush threat whenever the Jets feature Ryan's 46 schemes.
With Darrelle Revis continuing to lock down the back end and the underrated David Harris tackling anything that moves, the Jets have enough weapons and schemes to get back to their best.
Why is experience such an unpopular trait in a defense? Some may say the Pittsburgh Steelers are too old, but their collection of smart and aggressive veterans make Dick LeBeau's complex system possible. They will continue to dominate this season.
In fact, it is the arguably-needed infusion of youth that will prevent them from retaining their No. 1 defensive ranking from 2011. The key will be if fourth-round rookie Alameda Ta'amu can replace Casey Hampton at nose tackle.
Hampton doesn't receive a lot of headlines, but the 12-year pro is difficult to move off the middle. His ability to draw and occupy double-teams is crucial to Pittsburgh's defense.
The Steelers certainly missed Hampton when he succumbed to an ACL injury, and his return to the starting line-up is in doubt, according to NFL.com. Replacing the 34-year-old will be no easy task.
The San Francisco 49ers have a wealth of defensive talent, and they will be even better this season than they were in 2011. The 49ers defense is deep at every position and has the playmakers who allow them to keep things simple schematically and just play fast and run to the ball.
That led to a league-leading turnover ratio last season—forcing that many takeaways is not luck.
It's difficult to identify the best unit on San Francisco's defense, but their powerful three-man line probably makes the strongest case. Justin Smith rightly receives his share of plaudits, but fellow defensive end Ray McDonald is certainly no weak link. However, nose tackle Isaac Sopoaga is the focal point of the front.
Aldon Smith is regularly added to the mix, and he has already shown the ability to be a dominant pass-rusher. His first-step quickness and brute strength make Smith too much to handle for most blocking schemes.
Those fortunate enough to make it through the line then have to contend with the best inside linebacker combination in the NFL. Patrick Willis and NaVorro Bowman are fast, smart and physical and excel in run support, blitzing and coverage.
Yet it is the man who directs the defense who arguably plays the most important role. Vic Fangio is a true 3-4 guru, and his intelligent play-calling allows the 49ers to maximise the talents of this star-studded group.
While not quite as talented as the 49ers, the Houston Texans defense should edge them in the rankings in 2012 thanks to a slightly more favourable schedule.
Wade Phillips' blitz-happy unit should feast on an AFC South division with plenty of questions at the quarterback position. The Tennessee Titans have yet to declare a starter between Matt Hasselbeck and Jake Locker, and the jury is still very much out on Jacksonville Jaguars youngster Blaine Gabbert.
First overall draft pick Andrew Luck can be expected to experience his share of struggles with the rebuilding Indianapolis Colts. The Texans also face shaky offenses in the form of the Jets, Miami Dolphins and Minnesota Vikings.
Those games should ensure a stingy yards-yielded-per-game average for the Texans in the defensive rankings.
They have boosted their already potent pass rush with the addition of rookie Whitney Mercilus. College football's sack leader in 2011, Mercilus is the perfect weapon for Phillips. He joins Connor Barwin and Brooks Reed to form a dangerous trio of edge-rushers.
Youngster J.J. Watt should continue to improve, and Johnathan Joseph remains the perfect man-coverage specialist for Phillips' attacking system. This Texans defense can be even better than 2011's second-ranked group.