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CHARLOTTE — It is 3 a.m., the morning after the Panthers defense smothered the Jets with four sacks and a pick-six in a 30-20 victory.

You would think Sean McDermott, the Panthers' defensive coordinator, would be sleeping soundly, perhaps with a slight grin on his face. Instead, his eyes are open, and he is restless.

It is not the victory over the Jets that is replaying in his head. It is the 31-13 loss the previous week to the Saints.

Within an hour, McDermott will be back at his desk, trying to devise a way to make Drew Brees look like Geno Smith in a Panthers-Saints rematch on Sunday, this time on the Panthers' turf.

"It's that time of the year, so close to the end," McDermott said. "You think of the importance of the game we are playing in. It's the Saints, a division opponent, at home, and we just played them two weeks ago. This is what you do this for."

It is a chance for the Panthers to prove they have what the numbers say they have—one of the finest defenses in the NFL. The skeptics say this defense might be a bit of a mirage, and they have their reasons.

On one of the best defenses in football, you expect to see a plethora of Pro Bowlers. You expect to see former first-round picks everywhere. And you expect to see a lot of rich dudes. You don't see any of that on the Carolina Panthers.

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You see one player who has played in a Pro Bowl, safety Quintin Mikell. He was picked up in September after getting cut by the Rams. That Pro Bowl was four years and two teams ago. He made it as an alternate.

You see only three first-rounders—two of whom, Luke Kuechly and Star Lotulelei, aren't even halfway to being vested for their pensions. The third, Thomas Davis, is the only player in NFL history to come back from tearing his ACL three times.

You see only two defenders on the active roster, end Charles Johnson and Davis, who take up more than $3 million of cap space this year. According to Spotrac.com, the Panthers have committed $38,610,862 in cap space to their defense. That's the third-lowest amount in the NFL behind only the Jaguars and Raiders.

Here is what else you see on the Panthers defense. You see three undrafted rookies—cornerback Melvin White, safety Robert Lester and defensive end Wes Horton—playing significant roles.

You see a starting safety, Mike Mitchell, who never was a regular starter in four previous seasons in Oakland. He had to step up here after a season-ending injury to Charles Godfrey in the second game. You see journeyman Chase Blackburn taking the place of Jon Beason, the former leader of the defense who was traded in October. And you see a veteran who had been out of the NFL for two years starting at defensive tackle in Colin Cole.

All of which makes what the Panthers have accomplished nothing less than remarkable. The stories of the Saints defense and Chiefs defense have been told more frequently. Cam Newton has taken more of the spotlight, and the "Riverboat Ron" thing quickly became legend. But the story of the Panthers defense could be the one that is being retold 10, 20 years from now.

How did the Panthers defense happen? Just two years ago, this unit ranked 28th in the NFL in yardage allowed. Last year, it moved up to 10th. And now the Panthers are ranked second, behind only the Seahawks.

What is clear is the whole of the Panthers defense is greater than the sum of its parts. That points to a few things: Coaching, leadership, chemistry.

McDermott is the appropriate coach to coordinate this group. Fired by the Eagles, he was given a second chance by his old colleague Ron Rivera, now the head coach in Carolina. ESPN analyst Jon Gruden said what McDermott and his staff are doing is "one of the best defensive coaching jobs I've seen."

The Panthers are not doing it with smoke and mirrors, or with bells and whistles. It's good, old-fashioned, fundamental defense—the kind you usually have to look in the archives from past generations to see.

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It is not by accident that the Panthers generally are gap-sound. They get off blocks, they run to the football, they don't miss many tackles and they use good technique. McDermott and his staff go heavy on the fundamentals in practices, starting in OTAs, and they don't let up.

"It's who we are," he said. "And it's how we play."

In his early days with the Eagles, McDermott was a glorified gofer for Andy Reid, doing everything from making sure the team was complying with CBA rules to driving Reid's kids to appointments. He climbed the ladder in Philadelphia while learning under the late defensive mastermind Jim Johnson.

But when McDermott came to Carolina, he didn't just take a photocopy of Johnson's playbook and put a cat logo on the front page. With Rivera as an overseer, McDermott used some of the Eagles concepts but evolved the scheme to reflect changes in the league and Panthers personnel.

"He is a big student of the game," said Mikell, who was with McDermott in Philadelphia. "He's taken things he's learned over the years from Ron, (Steve) Spagnuolo, (Bill) Belichick, (Mike) Zimmer, all the defensive coordinators over the years. This defense is completely different from the one back in the day."

In Carolina, McDermott doesn't have All-Stars in the back end like Brian Dawkins, Troy Vincent, Al Harris or Bobby Taylor. Gruden has called the Panthers secondary "The Legion of Whom." It's a takeoff on the Seahawks' "Legion of Boom," and it points to the fact that they have a bunch of defensive backs most people never heave heard of. So McDermott has had to protect his no-names.

"It's about putting players in position to be successful, and not putting them in positions where they can't be successful," McDermott said. "If we're built for man, we'll play man. If we're built for zone, we'll play zone."

Under McDermott, the Panthers have become predominantly a fire-zone team, whereas Jim Johnson preferred his blitzes man-to-man. Mikell said the Eagles coverages and blitzes usually could be exposed by offensive motion. That isn't the case with the Panthers defense.

This defense also takes fewer chances with high-risk blitzes than Johnson's did. The Panthers defense has every potential receiver accounted for on every blitz, which is a departure from the Johnson way of doing things.

This approach has worked well. The Panthers' blitz-sack percentage of 14.75 headed into Week 15 was best in the league, according to Stats LLC. And the Panthers got heat on the QB even during the stretch when Charles Johnson was injured.

Really, the Panthers are mostly a four-man rush defense. They haven't had to be dependent on bringing extra men to get pressure, which has been part of their secret. "I've been behind some salty defensive lines in my career," Blackburn said. "These guys here, they're good."

Kuechly said McDermott "lets the D-line go and hunt, and he lets the linebackers run around. That's what we're good at."

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Kuechly seems to be good at everything. If there is a better middle linebacker in the league than the 22-year old second-year man out of Boston College, no one has seen him.

He has incredible games that draw rave reviews, like when he forced a fumble and intercepted a pass on subsequent drives against the Ravens in the preseason. And he does incredible things that hardly get noticed.

Just the other day, Kuechly created a buzz on the practice field when he outran the entire defense to the ball-carrier on a toss play. "Just a phenomenal athlete," Mikell said.

He is valuable to the Panthers for so much more than his athleticism, though. The real reason Kuechly is a Defensive Player of the Year candidate is he has made teammates better.

It started to become clear last year when he took over at middle linebacker and filled the Panthers' side of the line of scrimmage with pre-snap chatter. Prior to that point, it was quiet enough to hear the whistle of a touchdown pass. It was only after Kuechly figured things out that others started figuring things out, and then the defense fell into place.

Kuechly's pre-snap checks have enabled teammates to play with confidence. His tackles have enabled them to play with abandon. "There is an assurance as far as the front four is concerned that the guy behind them is going to make the play and cover up for them," Rivera said.

It isn't just on game day when the Panthers defense is impacted by their middle linebacker. It's every day of the week.

"These are guys who love to come to work every day, and Luke is the catalyst for that," McDermott said. "He's a great leader. He came in very humble as a rookie. He is the type of guy who, if you're sitting at a lunch table, he'll say, 'Can I get you anything?' It's not fake. It's who he is, how he was raised."

If Kuechly provides the blueprint, Davis brings the nails. McDermott calls Davis the "eye of the tiger of our defense," and says he and Kuechly provide a great combination of leadership.

Kuechly appreciates the confidence and trust coaches show in the players. "The biggest thing with Thomas and I and the guys up front is they put it on us," he said. "If we see something, we can make a change. And he takes what we see during the week and implements it in the game plan."

McDermott's suggestion box may be overflowing this week, and that's cool with him. The issue this former national prep champion wrestler will grapple with is how much he should change up the game plan in the Panthers' rematch against the Saints.

He can take solace that Panthers allowed only 10 points in the second half of the first game after a disastrous second quarter in which they were torched for three touchdowns. It was the only game of the year in which the Panthers surrendered more than two touchdowns.

"It's like a wrestler," McDermott said. "You want to wrestle your style of match. You want to acknowledge what they do, but you can't get away from what you do and what has made you successful to that point. We have to do a better job this week than we did the first time of staying true to our identity."

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After halftime in the first game, the Panthers' DBs played more physically against the Saints receivers, and that helped. This game could come down to the Carolina secondary again, which Jets receiver Santonio Holmes famously said was "probably the weakest link" on their defense.

No one has called Holmes a liar. But they have called him a motivator. After he made that statement last week, Panthers players started a texting chain until every member of the defense was riled.

And just in case anyone still was unaware, McDermott mentioned it in a defensive meeting. And then Rivera mentioned it in a team meeting. What's interesting is it wasn't just the secondary that took offense to the slight. It was the whole defense, the whole team.

On Sunday, cornerback Captain Munnerlyn had two sacks and an interception that was returned for a touchdown. Holmes had just two catches for 14 yards. Geno Smith was held to 167 passing yards.

But Smith is not Brees.

The truest test of the Panthers defense comes Sunday.

Dan Pompei covers the NFL for Bleacher Report.