If the old saying “defense wins championships” holds true, then the players on this list should be invaluable to their respective teams.
When it comes to evaluating which player is most important to his team’s defense, one must consider a variety of factors. Does his skill set fit a need? Does his style fit the system? Where does he rank in the locker room? Is he a leader? Is he a one-year wonder, or is he established?
Don’t forget that each team’s strengths and weaknesses are unique, and that all evaluations are skewed to fit team needs with regard to its current situation.
Not only is Patrick Peterson the Arizona Cardinals’ primary punt returner, but he's also the most explosive playmaker on the defensive side of the ball.
Although he lines up along the outside, he still finished his rookie season as the team’s fifth leading tackler with 64 total stops.
Peterson is an elite athlete who has blazing speed and attacks the ball like a wide receiver. However, he is still prone to poor technique in coverage and appeared a bit lost in zone schemes.
If the LSU product uses this offseason to hone his craft, expect the 21-year-old to stabilize and improve a secondary that ended the season ranked 17th.
With Curtis Lofton signing with divisional rival New Orleans, the Atlanta Falcons are expecting Sean Weatherspoon to step in and fill the void left by last year’s leading tackler.
Aside from 34-year-old John Abraham, the Falcons lack a consistent pass-rusher.
Defensive end Ray Edwards was expected to complement him on the other side but tallied only 3.5 sacks during his first year in Atlanta.
While his primary responsibility isn’t to rush the quarterback, Weatherspoon’s four sacks tied for second most on the team. He also recorded 115 tackles in 2011.
Expect new defensive coordinator Mike Nolan to send Weatherspoon in more blitz packages during this upcoming season.
Ngata had five sacks in 2011.
Although the reigning Defensive Player of the Year resides in Baltimore, Terrell Suggs is expected to miss the entire 2012 season after tearing his Achilles tendon.
This means that the Ravens will look for rookie linebacker Courtney Upshaw and Haloti Ngata to fill in for their leading pass-rusher.
Since it’ll be an uphill battle for Upshaw to get acclimated to the NFL, Baltimore will lean heavily on its 330-pound nose tackle.
As the anchor of the team's 3-4 front, Ngata is disruptive against the run and the pass.
He possesses an explosive first step and routinely draws double-teams. By occupying multiple linemen, his teammates are afforded free paths to the quarterback.
If the Ravens return this season as a top defensive unit, expect Ngata to have a monster year.
Defensive tackle Marcell Dareus led the Buffalo Bills with 5.5 sacks as a rookie.
That pretty much sums up the pass-rushing woes of a team that totaled only 29 sacks in 2011.
By signing Mario Williams away from the Houston Texans, Buffalo immediately upgraded its pass rush and made the most notable acquisition of the offseason.
Williams is an extremely versatile player who has thrived as a 3-4 linebacker and a 4-3 defensive end.
If you disregard his rookie season, the six-year veteran has played in 66 games and recorded a total of 48.5 sacks.
His relentless style of play and ability to bring pressure bodes well for an already aggressive secondary.
Williams will improve the play of the entire front four and prove that he’s worth the $100 million bill.
The captain of the Carolina Panthers defense suffered a left ankle injury during last year’s Week 1 contest that cost him the rest of the season.
Before that, Jon Beason had led the Panthers in tackles for four straight seasons and averaged more than 135 stops.
Although returning from injury, the 27-year-old remains as one of the top middle linebackers in the league and will look to improve a defensive unit that allowed over 130 rushing yards per game.
First-round selection Luke Kuechly projects to be the starting SAM linebacker for the Panthers and will develop the proper way as he plays alongside the three-time Pro Bowler.
Julius Peppers is arguably the most athletic defensive end the NFL has ever seen.
At 6’7”, 287 pounds, the 10-year veteran still has the agility and fluidity to chase down elite escape artists like Michael Vick and Cam Newton.
The North Carolina product has missed only six games during his entire career and has played in all 32 contests during his two-year stint with the Chicago Bears.
Peppers has collected a total of 100 sacks and forced 36 fumbles during his NFL tenure. So when he gets his hands on the quarterback, there’s a good chance that the signal-caller is going to drop the ball.
Although he was constantly double-teamed in 2011, Peppers still collected 11 sacks.
His domination is what afforded teammates Israel Idonije and Henry Melton easier paths to the quarterback.
Idonije and Melton finished last season as the Bears’ second- and third-best pass-rushers, yet they only totaled one more sack than Chicago’s most important defender.
Although Carlos Dunlap recorded an astounding 9.5 sacks in 2010, he was plagued by a hamstring injury that caused him to miss time during last season.
This left Geno Atkins as the Cincinnati Bengals' best pass-rusher and interior lineman.
As a defensive tackle, Atkins applied constant pressure up the middle as he collected 7.5 sacks, 47 tackles, two forced fumbles and two pass deflections.
The second-year pro took tremendous strides as a run-stopper and led the Bengals to the 10th-best run defense.
With the AFC North featuring two defenses that seem to rank in the top five annually, expect this group of young Bengals to join them shortly.
Joe Haden will be entering his third year as a pro but has already established himself as the Cleveland Browns’ best defender.
Last year, linebacker D’Qwell Jackson led the team with 158 tackles but was also a major part of a run defense that ranked 30th in the NFL.
In comparison, Haden led a secondary that allowed less than 185 passing yards and ranked second overall.
Although the Florida product recorded zero interceptions in 2011, he remains one of the top defenders at his position.
The 23-year-old is well-rounded in all facets of the game and isn’t afraid to attack receivers at the line of scrimmage, nor is he timid in run support.
Rob Ryan’s aggressive style of defense revolves completely around DeMarcus Ware.
In the Dallas Cowboys' 3-4 scheme, the cornerbacks are asked to play man-to-man press coverage because it affords them more time to get to the quarterback.
Without Ware and his 19.5 sacks, the Cowboys would be completely absent a pass-rushing threat.
Needless to say, this wouldn’t bode well for a unit that’s based on pressure.
Throughout the entirety of his seven-year career, Ware has played with a consistency that forces offensive coordinators to alter their blocking schemes and play-calling.
So while it isn’t always obvious, you should beware that D-Ware influences the game in more ways than one.
With Brian Dawkins' recent retirement, the Denver Broncos will need a veteran presence on a relatively young defense to command respect with reputation and play.
Champ Bailey will be entering his 14th season, yet he remains one of the NFL’s premier cover corners.
Since entering the league with tremendous athleticism, the future Hall of Famer has evolved his game. No longer does he rely on his speed or long arms to defend passes, but rather his knowledge and past experiences.
Although he only played in 13 games last year, Bailey still tied for the team lead in pass deflections and interceptions.
His ability to shut down receivers is the reason why Elvis Dumervil and Von Miller have been able to enjoy so much success.
If the Broncos hope to generate a consistent pass rush, look for Bailey to factor into the equation.
Although Ndamukong Suh is a disruptive force up the middle, he remains too immature and has a tendency to draw costly penalties.
The Detroit Lions also have tremendous depth along their front-four—which works against the young defensive tackle for this honor.
Head coach Jim Schwartz loves the wide-nine alignment.
While this scheme allows his defensive line to be extremely aggressive, it also leads to occasional recklessness.
This means that the Lions need the proper linebacker to support their front.
Stephen Tulloch is that guy.
Last season, Tulloch led the team with 111 tackles and entered free agency as the Lions’ primary target to re-sign.
The six-year veteran is coming off of three straight seasons with at least 110 tackles and is the absolute perfect linebacker to complement the wide-nine scheme.
The Green Bay Packers were absolutely atrocious on the defensive side of the ball last season. However, it was no fault of Clay Matthews.
Although he only recorded six sacks in 2011, the former USC star was constantly double-teamed off the edge, yet still managed to generate consistent pressure.
The arrival of first-round pick Nick Perry is going to force the three-year pro back to the right outside linebacker position, where he spent his first two seasons and collected 23.5 sacks.
Regardless of where he begins in the formation, you can expect Matthews to end up at the quarterback more often than not in 2012.
It’s no surprise that the arrival of Johnathan Joseph in 2011 coincided with the Houston Texans’ first AFC South championship and a trip to the playoffs.
But along with Joseph, the Texans brought in defensive coordinator Wade Phillips, who immediately implemented a switch from the 4-3 front to a 3-4 scheme.
The change was instilled to create a more consistent pass rush and allow for exotic blitzes to come in confusing personnel packages.
While this sounds like a great plan on paper, it takes tremendous coverage on the outside to give blitzers enough time to reach the quarterback.
In his first year as a Texan, Joseph did more than hold his own and helped his defense limit opponents to less than 190 passing yards per game (third).
His efforts also earned him a trip to the Pro Bowl and this honor.
The Indianapolis Colts have one of the best pass-rushing tandems in the NFL, which makes separating Dwight Freeney and Robert Mathis nearly impossible—even on this list.
Aside from their two stud defensive ends, the Colts' defense is completely absent of star power.
The dynamic duo has teamed up for a decade, combining for 21 years of service, 681 tackles, 186 sacks and —what sets them apart from any other pass-rushing ends—82 forced fumbles.
With Freeney and Mathis using their explosive speed on the edge, opposing quarterbacks have little time to read the defense, let alone get comfortable in the pocket.
Although the Colts will be using Freeney as an outside linebacker during their 2012 transition into a 3-4 defense, it’s safe to assume that he will remain dominant.
Although Paul Posluszny led the Jacksonville Jaguars in tackles last season, it’s Daryl Smith who has been the model of consistency for the franchise.
Smith has played in every single contest during the last three seasons and has averaged over 100 tackles per year during that span.
He has shown the versatility to play multiple linebacker positions and play them successfully.
The nine-year pro has reliable instincts that guide him toward the ball and impressive coverage skills that make him a solid three-down player.
Smith lets his play do the talking, which is exactly why he has so much command in the huddle.
While the Kansas City Chiefs have an explosive safety in Eric Berry and a reliable tackler with Derrick Johnson, they still need a consistent pass-rusher to make their 3-4 scheme effective.
Enter Tamba Hali.
Hali will begin his seventh season as a player who has only missed one game during the entirety of his career.
The Penn State product has amassed a total of 352 tackles, 53.5 sacks and 22 forced fumbles for the Chiefs while playing both defensive end and outside linebacker.
His ability to create separation by using his hands is something that should be duly noted and applauded.
Hali recorded 12 sacks in 2011, with no one else on the Chiefs roster reaching even half of his total.
Fans tend to forget that the ex-Canadian Football League star is already 30 years old but only three seasons deep into his NFL career.
Ever since Cameron Wake joined the Miami Dolphins in 2009, he’s been a disruptive force coming off the edge.
He carries a chip on his shoulder and an extremely quick first step onto the field with him.
Wake managed to collect 5.5 sacks during his first season with the Dolphins as a situational pass-rusher. Ever since, he has earned himself a starting role and has led the team in quarterback takedowns for consecutive years.
He has a motor that never stops and sets the tone extremely well for the rest of the defense.
It’s not just that Jared Allen has collected 62 sacks in the past four seasons without missing a game, but rather the fact that those 62 stops have resulted in 394 yards.
He can run around you or simply right through you.
His ability to reach the quarterback has single-handedly helped the Minnesota Vikings win ballgames in today’s pass-happy NFL.
And while some defensive ends make their living as a pass-rushing specialist, you'd better not consider Allen in the same group.
The four-time All-Pro is extremely disciplined against the run as well and has an uncanny nose for the ball. In the past two seasons, Allen has recorded three interceptions to go along with 126 tackles—making him a multidimensional weapon on the edge.
The New England Patriots defense revolves completely around Vince Wilfork and his disruptive play in the middle.
Thanks to his ability to draw consistent double-teams, Andre Carter and Mark Anderson both enjoyed double-digit-sack seasons in 2011.
Carter is currently a free agent, while Anderson has taken his talents to Buffalo.
With half of last season’s total sack production missing, the Patriots will need Wilfork to play with more aggression and consistency.
The nose tackle has tremendous strength and routinely bullies centers off the point of attack. Once he gets into the backfield, his presence alone causes opposing running backs to scatter to the edges and into the arms of Jerod Mayo and Rob Ninkovich.
It’s likely that the New Orleans Saints will play the entire season without starting middle linebacker and team captain Jonathan Vilma.
When you add in the fact that defensive coordinator Steve Spagnuolo is entering his first season with the team and will be without head coach Sean Payton, fans should begin to question the validity of the Saints defense.
Luckily for the Saints, they’ve used the offseason to sign Curtis Lofton.
Not only did Lofton come from their divisional rivals, but he is also an exceptional tackler.
The fifth-year pro will be expected to expand his game and replace Vilma as the defensive play-caller while becoming a three-down linebacker.
If Lofton is unable to bring leadership and stability to a rocky organization, look for New Orleans to be supplanted as NFC South champions.
Even with a stacked defensive front, Mathias Kiwanuka is the one New York Giant who stands tall.
As the team entered the 2011 season with a trio of stud pass-rushers that included Justin Tuck, Osi Umenyiora and Jason Pierre-Paul, Kiwanuka was more than willing to make the switch to outside linebacker.
Along with his 84 tackles, 3.5 sacks and 12 run stuffs, Kiwanuka brought versatility and veteran leadership to Tom Coughlin’s defense.
The Boston College product will continue his role as a stand-up player in 2012 but is still talented enough to generate pressure from the outside.
Now with one year of playing experience and a full offseason to learn his new position, Kiwanuka is guaranteed to build upon his previous season’s successes.
Rarely do the New York Jets get to the quarterback without bringing extra defenders.
As a collective unit, the defense finished the 2011 season with a total of 35 sacks.
And if not for the play of Darrelle Revis, that number would be significantly lower.
Revis’ ability to interrupt routes and occupy receivers is what allows his teammates extra time to collapse the pocket and generate pressure.
He essentially shuts down one whole half of the field and is versatile enough to cover the slot when necessary.
His physical and aggressive style of play sets the tone for the entire defense and explains why he epitomizes the definition of “Mean Green."
Tyvon Branch has quietly recorded more than 100 tackles in three consecutive seasons, so he definitely deserves some recognition.
Last year, he not only led the team in that category, but he also eased the sting of mistakes made by his teammates.
He played in all 16 contests and provided stability for a secondary that was getting over the loss of Nnamdi Asomugha.
Branch was on the field for 1,167 snaps of action and was only flagged for two penalties throughout the entire season.
His discipline in coverage and as a leader are the exact qualities that new general manager Reggie McKenzie is looking for as the team reshapes its image.
For a team that’s loaded with Pro Bowlers on the defensive side of the ball, it may seem premature to label an incoming middle linebacker as its most important player.
However, if anyone watched the Philadelphia Eagles during the first half of last season, they’d notice a gaping hole in the middle of their defense.
The Eagles spent 2011 integrating Jim Washburn’s wide-nine scheme. And although it resulted in 50 sacks, the run defense definitely took a hit.
Ryans will start the season as the quarterback of the unit and will be expected to stop opposing running backs once they get past the front four.
If he can return to his old Pro Bowl form, expect the Philly defense to dramatically improve in all facets.
The Pittsburgh Steelers have a defensive unit that seems to never run out of playmakers. However, none of them can impact a game the way Troy Polamalu does.
Although Polamalu routinely lines up 15 yards away from the snap of the ball, he usually ends up around it.
Thanks to his elite instincts and freakish athleticism, the Tasmanian Devil can go from the secondary to the opponent’s backfield in the blink of an eye.
His feel for game situations and player tendencies gives him a distinct advantage on plays like this.
The former USC star isn’t a very vocal player, but he lets his play do the talking.
Just because Eric Weddle has established himself as one of the best run-support safeties in the league doesn’t meant he won’t receive vitriol from San Diego fans if he can’t replicate last season’s interception numbers.
Although he tied for the league lead with seven interceptions in 2011, Weddle has been known to be notoriously bad at catching the ball.
The highest-paid safety in NFL history will have to shed this label while the Chargers develop rookie Melvin Ingram into a reliable pass-rusher.
If his play drops off even one bit, expect the Chargers pass defense to be significantly worse in 2012.
Ever since entering the league in 2007, Patrick Willis has been challenging Ray Lewis for the distinction of being the league’s premier middle linebacker.
The five-year pro has the ultimate blend of speed and power, which makes him a nightmare against the run and more than capable of sticking with elite tight ends in coverage.
Willis’ innate ability to intimidate receivers at the line of scrimmage helps him separate them from the ball.
He rarely misses a tackle and has yet to miss a Pro Bowl.
His presence and leadership have given younger teammates like NaVorro Bowman and Aldon Smith the confidence to develop into integral parts of the San Francisco defense.
The Seattle Seahawks secondary finished the 2011 campaign ranked as the 11th-best unit and is comprised of a core of young talented players.
This makes it extremely difficult to justify the selection of just one player from that group for the honor of most important defender.
While Seattle selected Bruce Irvin in the first round to fill the role of a much-needed pass-rusher, it is second-round pick Bobby Wagner who will play a larger role in 2012.
Thanks to the departure of David Hawthorne, Wagner will begin the season as the team’s starting middle linebacker, which gives the 21-year-old a huge burden to shoulder as he enters training camp and gets acclimated to the pro game.
Not only will the Utah State product be responsible for relaying play calls from the sidelines, but he will also be the one who puts his teammates in the proper alignment.
If Wagner is unable to adapt quickly, expect the Seahawks to miss the playoffs for a second straight year.
The St. Louis Rams only gave up 206.3 passing yards per game last season but still needed an extreme makeover in the secondary.
New head coach Jeff Fisher brought in one of his former players, free agent Cortland Finnegan, to lock down one half of the field.
But it didn’t end there.
Not only did the Rams give Finnegan a five-year, $50 million contract, but they also invested two premium draft picks on cornerbacks.
Third-round selection Trumaine Johnson spent his entire collegiate career covering lesser receivers in the Big Sky Conference, while second-rounder Janoris Jenkins comes with his own off-field baggage.
If St. Louis wants a proper return on these selections, look for Finnegan to play a crucial role in the team's development.
Although the Tampa Bay Buccaneers closed out 2011 by allowing an average of 34.9 points during a 10-game losing streak, they’ve quietly assembled a young defensive line that’s loaded with talent.
Look for that group to collectively improve on a run defense that ranked dead last in the NFL.
This leaves 37-year-old Ronde Barber and the oft-troubled Aqib Talib as leaders of the secondary.
With Barber moving from cornerback to safety, not only will Talib be expected to lead the back end of the Buccaneers defense but also transcend his level of play to “elite” status.
The four-year veteran has shown flashes of brilliance during his short career but will need to remain aggressive and consistent for Tampa Bay to contend in the competitive NFC South.
Without Cortland Finnegan and tremendous safety play, the young cornerback tandem of Alterraun Verner and Jason McCourty will struggle to uphold the back end of the Tennessee Titans defense.
This means that defensive coordinator Jerry Gray will be counting on two-time Pro Bowler Michael Griffin to stabilize the secondary and erase the mistakes of his teammates.
Griffin will be entering his sixth season and is coming off of a mediocre 2011 campaign in which he recorded 75 tackles, two interceptions and one forced fumble.
If the ex-Longhorn can return to his 2008 form and become more of a playmaker, it would alleviate the pressure on the entire defense and an unstable offense.
Although it’s not always apparent, the Washington Redskins have one of the best sets of 3-4 linebackers in the entire league.
The leader of that group is none other than 37-year-old London Fletcher.
Rarely does an offense confuse him, and rarely does a ball-carrier bypass him.
Fletcher has never missed a game throughout his 15-year career and has collected a total of 1,782 tackles.
His presence and command of the huddle are invaluable traits for a relatively young linebacking corps.
As Fletcher enters his third year under Mike Shanahan and his first with Robert Griffin III, expect him to catch a whiff of the youthful exuberance that seems to be spreading around Washington.