How the Lions Became an Elite Defense and Why the Dominance Will Continue

Look up almost any meaningful defensive statistic and you'll find the Detroit Lions at or near the top of the rankings after four games this season. 

While numbers often lie, these don't. The Lions have a legitimate argument for being the NFL's top defense at 2014's quarter pole, and there's no reason to think a regression is approaching. 

Four games in, the Lions defense ranks first in total yards (267.3 per game), second in passing yards (186.5), fourth in points (15.5) and sixth in rushing yards (80.8). Digging deeper than the surface stats also reveals a top defense. Detroit currently ranks first in yards allowed per play (4.6) and first downs per game (16.8), third in sack percentage (7.9), fourth in third-down conversion rate (34.0 percent), opponent passer rating (77.4) and yards per pass attempt (5.9), and seventh in yards per rush (3.4).

The only premier defensive stat the Lions aren't found near the top is takeaways, where Detroit's five (three interceptions, two fumble recoveries) rank 19th overall. But the overall efficiency of the defense has made the lack of turnovers mostly a moot point. 

How have the Lions, despite not making any noticeable additions personnel-wise this past offseason, ascended the rankings? And why will the Lions likely stay among the best for the rest of this season? 

Four main pillars of the Detroit defense have either emerged or solidified:

Still Destructive Defensive Line

A long-standing pillar, Detroit's defensive line has remained a wrecking ball of sorts in 2014. The front four is once again a brick wall against the run and more than destructive enough against the pass. 

According to Pro Football Focus (subscription required), the Lions defensive line has already tallied 21 run stops this season, including five a piece from Ndamukong Suh and Nick Fairley. The two behemoths in the middle generally control the proceedings, using quickness to burst through gaps and strength to hold up and shed double teams. 

Since the start of 2013, the Lions have allowed the sixth fewest rushing yards. 

Equally impressive has been the way Suh and Fairley have attacked the passing game. The two have already combined for 22 total quarterback disruptions, which is the most by a pair of defensive tackles in the NFL. Suh's 14 disruptions rank second, behind only Kyle Williams of the Buffalo Bills (16). 

Fairley has the body of the run-stuffer but the quickness of a man much smaller. Below, Fairley can be seen nearly sacking Aaron Rodgers in Week 3—amazingly, while Rodgers is still playing out the run fake:

NFL Game Rewind

These are the kind of individual plays that allow Lions defensive coordinator Teryl Austin to play the run with six or seven defenders and rush the quarterback with only four. The defensive line powers Detroit's ability to routinely attack offenses with numbers on its side. 

Two Legitimate Cornerbacks

How long has it been since the Lions could claim to have two cornerbacks capable of consistently holding their own on the outside? In 2014, it's real. Starters Rashean Mathis and Darius Slay have emerged as a legitimate pair of cover corners.

Together, the 34-year-old Mathis and 23-year-old Slay have allowed a 51.1 completion percentage (23 completions on 45 targets) and a passer rating of only 65.9. The defense as a whole has given up just four passing touchdowns, which ranks fourth in the NFL. The Lions are pace to allow just 16 in 2014, which would be eight fewer than last season. 

	Targets	Comp	Yards	TD/INT	Passer Rating
R. Mathis	17	8	82	1/0	81.0
D. Slay	28	15	167	0/1	56.7
TOTALS	45	23	249	1/1	65.9

Slay, a 2013 second-round pick, has been a pleasant surprise. Of the 22 cornerbacks targeted 25 or more times this season, Slay's opposing passer rating of 56.7 ranks second. He allowed 98 yards in Week 4 against the New York Jets, but he also handled Jordy Nelson (two catches, 11 yards vs. Slay) a week earlier. 

On the other side, Mathis has been targeted less frequently per snap than wealthy cornerback Patrick Peterson of the Arizona Cardinals. According to PFF (subscription required), Mathis is also giving up just 0.59 yards per coverage snap (82 yards, 139 coverage snaps). For context, consider that Seattle Seahawks cornerback Richard Sherman is allowing 0.52 yards per coverage snap this season. 

Slay and Mathis might not be the best cornerback duo in the NFL. But they represent the best pair the Lions have featured at the position in some time, and they've helped drive Detroit's 60-yard improvement per game against the pass over last season. 

Impact of Glover Quin

Five safeties have played over 100 snaps and allowed a passer rating under 25.0 this season: Charles Woodson, George Iloka, Ha Ha Clinton-Dix, George Wilson...and Quin. Opposing quarterbacks have targeted him eight times but gained just 29 yards, with zero touchdowns and one interception.

But Quin's impact goes beyond the stats. His versatility is vital for the different mix of coverages the Lions prefer to play behind the front four.

Quin can line up as part of a two-high shell, like he did to help blanket Nelson and Randall Cobb in Week 3. He can sit back in center field as the lone safety, like the Lions primarily played in Weeks 1 and 2. And he can even come up and play like the slot, like he did eight times against the Jets in Week 4.

He's also no slouch against the run. According to PFF (subscription required), Quin has graded out as the 13th best safety in run defense this season.

Possessing a versatile safety is now more imperative than ever in today's NFL. Offensive variety can be used to manipulate the position, but having a player like Quin is the antidote. The Lions can move him around as their own chess piece, creating diversity in coverages and strength against the run. His addition in 2013 has provided a stabilizing effect to the back end of the Detroit defense. 

DeAndre Levy is a Star

Levy remains the best linebacker in football no one knows. Playing on the weakside of Detroit's 4-3, Levy uses instincts to attack downhill against the run and athleticism to cover running backs, tight ends and even receivers in space. 

This tweet from the Lions' official Twitter account sums up his impact:

While tackles are an overrated stat, "stops" are not. PFF considers any tackle constituting an offensive failure as a "stop." Last season, Levy was sixth among 4-3 outside linebackers with 48. He's third in 2014 with 20, putting him on pace for 80 this season. Translation: Levy doesn't just make hollow, meaningless tackles; his stops provide impact.

Speaking of impact, arguably no linebacker has been better at creating havoc in coverage. Levy's seven interceptions since 2013 rank first at the position (Karlos Dansby is second with five), and his 18 passes defensed are third among linebackers. 

Big plays have so far littered Levy's season. In Week 1, he made two tackles for losses and intercepted Eli Manning. Against the Packers, Levy dropped Eddie Lacy for a safety and had two passes defensed, including the dagger on Aaron Rodgers' fourth-down attempt to Jordy Nelson in the fourth quarter. In his two other games, Levy totaled 18 tackles and two tackles for losses. 

Levy was snubbed of a Pro Bowl nod last season. In 2014, the Lions' dominance on defense should provide the highlighting of his abilities necessary for league recognition. 

Leon Halip/Getty Images

Put all the pieces together, and the results have been consistently dominant. The Lions embarrassed Manning and the Giants in Week 1. The defense outscored Rodgers and the Packers offense 9-7 in Week 3. The Jets had seven three-and-outs and two turnovers last Sunday.

A season ago, the Lions held offenses to under 17 points three times. Detroit has already matched that number this season. 

At the season's quarter pole, the Lions look like one of the NFL's elite defenses. As long as all the pieces keep working in harmony, there's no reason to think that title will need removing.   

Zach Kruse covers the NFC North for Bleacher Report. 

Follow @zachkruse2