PHILADELPHIA -- Just about any way you slice it, the Philadelphia Eagles are one of the top defenses in the NFL statistically heading into Sunday's Week 17 matchup against the Washington Football Team (1 p.m. ET, Fox).

They're fifth overall in opponent yards per game (320.2), third in yards per play (5.0), second in limiting pass plays of 20 air yards or more (14), fourth in three-and-out rate (35 percent) and yards per rush (3.9), and 12th in points per game (21.2).

The unit has helped propel the Eagles (8-7) into playoff contention, and there's now buzz that first-year defensive coordinator Jonathan Gannon could be considered for some of the head coach openings this offseason.

If this all seems slightly shocking, it's because the Eagles' defensive surge has been sudden and dramatic. Consider: in Weeks 1-7, Philadelphia had one of the worst defenses in the league, ranking 24th in opponent points per game (26.43), 28th in opponent first downs per game (23.9) and 26th in third-down conversion rate (44.8%), to name a few. In Weeks 8-16, the Eagles' numbers shot up across the board, including to fourth in points per game (16.63) and eighth in both first downs per game (18.1) and third-down conversion rate (36.3%).

What's behind the turnaround? And are the recent results to be trusted? Let's take a closer look:

The QB factor

The Eagles had one of the most difficult opening schedules in the NFL. That's largely due to the quarterbacks they faced over the first half of the season, a group that included Tom Brady Tampa Bay Buccaneers), Patrick Mahomes (Kansas City Chiefs), Dak Prescott (Dallas Cowboys) and Justin Herbert (Los Angeles Chargers). The results were historically bad, as Philly allowed five different quarterbacks to complete 80-plus percent of their passes. That's striking. Between 1950-2020, the Eagles allowed just 6 quarterbacks to complete 80-plus percent of their throws (minimum 25 attempts), per ESPN Stats & Information.

Their opposing quarterbacks over the past six games? Teddy Bridgewater (Denver Broncos), Trevor Siemian (New Orleans Saints), Daniel Jones (New York Giants), Zach Wilson (New York Jets), Garrett Gilbert (Washington), Mike Glennon (Giants) and Jake Fromm (Giants).

When looking at the change in fortune, it starts with the level of competition the Eagles have faced of late.

"Of course, the opponent that you play ... always goes into it," said coach Nick Sirianni. "But this is the NFL. Any team is capable of doing anything at any time. And so we don't look at it like that. We do what we've got to do to win each football game."

Critical changes

Linebacker T.J. Edwards may not be a household name, but his impact on the Eagles' season can't be ignored.

Since taking over as the starting middle linebacker in Week 8, the team's defensive grade went from 25th (56.8) to fifth (75.1), according to Pro Football Focus, while opponent rushing yards per game dropped off a cliff from 133 yards per game (29th) to 79.8 (2nd).

Edwards, who brings a physicality to the position that was lacking before he took over, has the third-highest grade among linebackers since Week 8 (82.7) and ranks sixth in tackles over that span (56), per PFF.

The Eagles are 6-2 since Edwards took on a larger role.

"He's really settled in. He's the green dot and he makes all the front mechanic calls with the front. I mean, he's making the back end calls with the back-end guys, and he's just a really good communicator," Gannon said.

"You hear me talking about being emotionally stable. He's one of those guys that every once in a while I'll juice him in his ear and he just gives me a thumbs-up. ‘I got you, Coach,’ or, ‘T.J., get this done,’ ‘I got you, Coach,’ and then a call comes in. He's been a joy to be around. He's smart, tough, physical."

Gannon has made some effective tweaks to his scheme. From Weeks 1-7, his defense played the least amount of man coverage (26.7%) in the NFL. From Week 8 on, that rose to 44.4%, which ranks 17th. The defensive backs are allowing less cushion in the intermediate area of the field. And Gannon has turned up the heat: He's dialed up 72 blitzes over the last eight weeks compared to 40 over the first seven.

"Process-wise, I think guys are just more familiar with each other," said Edwards, who posted a career-high 16 tackles last week against the Giants. "The chemistry is there and you can feel that from coaches to players and players to players. We've all just grown as the year has gone on."

The offense's role

"Complementary football" is a term often used in NFL circles to describe how the offense can help the defense and vice versa. What's happening in Philadelphia is a prime example of it.

The rapid improvement on defense coincides with Sirianni's philosophical shift to a more ground-based attack on offense at the season's midway point. Over the first seven weeks, when Sirianni was leaning too hard on an inefficient passing game, the Eagles' defense ranked 31st in opponent time of possession (33:53).

From Weeks 8-16, when Philadelphia developed into the No. 1 rushing offense in the league, the Eagles' defense ranked fourth in opponent time of possession (27:19). That has something to do with their improvement against the run and on third down, sure, but it's also directly related to the ball-control style of offense Sirianni is now deploying. Less stress, better results. Pretty simple.

What's the bottom line?

Philadelphia's defense has improved significantly. Gannon has found his footing. He's identified calls and personnel groupings that are most effective, while the players have grown more comfortable in his system.

That said, it's fair to have a healthy degree of skepticism about the group, as it has still yet to prove that it can hold up against a top-end quarterback. The Eagles will get that opportunity in Week 18 against Prescott and the Dallas Cowboys, assuming Dallas isn't resting its starters, and certainly in the playoffs should the Eagles get in. They currently have a 65% chance to make the postseason, per ESPN's Football Power Index, in no small part because of the defense's improved play.

"I think we've done a good job of getting better every day and not listening to the outside noise. When the outside was telling our defense they stink, we didn't listen. We put our head down and we continued to work. When the outside is telling us now, ‘You're in the top 5 and you're awesome,’ we're not listening. We're putting our head down and working and trying to get better," Sirianni said.

"There is no secret. We're better now than we were a month ago because of the way our guys work and our philosophy of, hey, how do I leave this place a little bit better than I was yesterday?"