What is the secret behind Jason Babin's midcareer resurrection?
Is it that the former first-round draft pick was finally released from the shackles of playing out of position, or where he wasn't wanted, or low on the depth chart?
Or is it that Babin found his guru in Jim Washburn, the brutally honest defensive line coach who ran a scheme perfectly suited to his skill set?
Or could it be his one-track obsession with sacks, which some believe he pursues at the sacrifice of stopping the run?
Or maybe it's just a combination of the above, mixed with something Washburn said that Babin possesses more than any other pass rusher in the league: hustle.
"The reason he's a good football player is he's really quick, he's explosive, and he never stops," Washburn said last week. "Who in the league plays harder than Jason Babin?"
A reporter suggested the Eagles' Trent Cole, a two-time Pro Bowl defensive end.
"Not so," Washburn said. "I haven't seen anybody. . . . Trent Cole and Jason Babin play hard. But who chases the ball better than Jason Babin?
"You want me to just tell you: There's nobody in the league that plays as hard as he does. Sorry. I can go out there and make that statement."
DeMarcus Ware's or Jared Allen's position coaches may disagree, but Babin at least deserves to be mentioned among the candidates. Only the Cowboys linebacker and Vikings defensive end have more sacks than Babin's 271/2 over the last two seasons.
His 15 sacks this year are tied for second in the NFL, and with three games left to play, Babin has Reggie White's franchise record of 21 within his sights. His relentless pursuit of quarterbacks has been one of the few bright spots for an Eagles team that could be on the brink of postseason elimination when it hosts the New York Jets on Sunday.
To some of Babin's critics, the mere mention of Babin's name alongside White's is blasphemous. White set his mark in a strike-shortened, 12-game season while dominating just as much against the run.
That's become the rub against Babin - signed as a free agent in July after he resurrected his career last season in Tennessee under Washburn - and to an extent his position coach: All they care about is sacks.
"We're not doing good, they should be critical of us, they should talk in a negative way," said Babin, who hasn't been afraid to take on his detractors. "But they should understand what they're really talking about. I hate when they just use generalities."
If the Eagles were 8-5 instead of 5-8, Babin might not have been such a lightning rod. He may have seen more love thrown in his direction during his first go-around here, when he was an underdog backup. But when you sign a five-year, $28 million free-agent contract, you are no longer the underdog.
It's a shame, because Babin's riches-to-rags-to-riches story is one to embrace.
Babin gives much of the credit to Washburn, whom he followed to Philadelphia.
Sitting in the defensive line's meeting room at the NovaCare Complex - his lair, of sorts - Washburn ran film of his linemen getting after a quarterback as he turned up Jimi Hendrix's "Machine Gun."
"Look how good this goes together," Washburn said.
Hendrix laid down a lick as Sam Bradford took one from Cole.
The room is set up like a small home theater, but it's really Washburn's office. Motivational sayings and various artwork are splattered on the walls, the refrigerator, wherever. A reporter agreed they were for Eagles eyes only.
When the topic of Babin and how he was miscast in Houston came up, Washburn narrowed his eyes.
"He went to Houston and those guys just tried to make him drop, put a square in a round hole," Washburn said of the Texans, who made Babin their top pick in 2004. "He's not built that way. He's an undersized guy that they see as a hybrid, but he's not mentally wired to do all that other stuff."
When Babin rushed he got into the backfield, but he had trouble in coverage. Houston gave up on him after three seasons and Babin landed with the Seahawks, where he was caught in a tug-of-war between the front office and the coaching staff. He hardly played for a little over a season.
"Seattle was a dark time," Babin said. "I mean, I got shingles I was so stressed out there."
It was in Seattle, Babin said, that he changed his approach to his mental health and separated football from his family life. So when he drove home after practice to be with his wife, Sara, and two sons, he said he sat in his car for five minutes to "let everything go."
"Mental health is the idea of happiness, of being happy when you get to work," Babin said. "You enjoy this, you don't come to work dreading it. That approach creates positive energy, and then essentially you have a better practice, a better lift, a better meeting."
The Seahawks released him in early 2008 and Babin was out of the NFL until the Chiefs signed him two months later. He found a team with a 4-3 defense that allowed him to pass-rush, but there was a regime change after the season and he wasn't re-signed.
The Eagles called during training camp the following year. Babin made the team, but was only a role player. After the season both parties agreed to go their separate ways. Babin wanted to start and the Titans were willing to give him the opportunity.
Washburn said that he loves to scour the waiver wire looking for lean, high-motor pass rushers whom other teams discarded. The 6-foot-3, 267-pound Babin fit the mold.
"He ain't 260. He's skinny. He's little," Washburn said. "When [Tennessee] went to the Super Bowl and played with the old Jevon Kearse, not the one you know - "The Artist Formerly Known as The Freak" - he weighed 243 the day before the Super Bowl."
Babin started from Week 1, racked up 121/2 sacks for the Titans, and was voted into his first Pro Bowl. He took Washburn and his wife to Honolulu along with his family. The Washburns baby-sat Babin's sons one night.
"They call us, 'Coach and Nana,' " Washburn said. "That's what our grandkids call us."
Washburn and Babin cemented their relationship in the offseason when the coach and his daughter visited Babin's Texas farm. They did some shooting with Babin's automatic shotgun.
"We're just blowing the - out of stuff and it was so much fun," Washburn said. "And Jessica was like, 'You guys have so much in common.' And I was like, 'I know.' "
So when Washburn took the Eagles job and the Titans made little effort to re-sign Babin, it was a foregone conclusion that he would follow his mentor and Washburn's wide nine.
The wide nine - in which the ends line up in the nine technique or outside the tight end - became the basis for the Eagles' new defense. And in Washburn's scheme the linemen were no longer asked to read run or pass but to rush with ferocity.
"When it works right and everyone's in the right spot, it's not like bend-and-don't-break defense," Babin said. "It's a zero, smash-you-in-the-face, put-you-on-your-back kind of defense."
Washburn's linemen were getting their sacks, but running backs were cruising through wide gaps that the Eagles' inexperienced/mediocre linebackers and safeties couldn't effectively fill. It took several games before the wide nine was narrowed on most obvious run downs.
Babin and Washburn started to be accused of caring only about sacks. Opposing offenses were targeting Babin's side of the line more than other spots and have averaged more yards - 6.5 - with the end often being caught rushing too far upfield.
When Seattle running back Marshawn Lynch gashed through a hole between Babin and linebacker Akeem Jordan and ran 40 yards for a touchdown earlier this month, the howls only grew louder. Babin took to Twitter when he said he read criticisms on Bleacher Report, a website composed of fan-written stories, and from a few other articles sent to him by his wife.
"Wow reading some of these articles, if u were in [locker] room & saw some of these reporters, u would understand," Babin wrote over two tweets. "its like they never saw a Tbrush, shower, and problly the only time they leave their mom's basement."
Washburn defended Babin's play and said he's actually become stouter against the run this season. Taking to the chalkboard, Washburn diagrammed how the ends in the wide nine are to rush upfield and squeeze running backs inside to the tackles or an unblocked linebacker or safety.
"There might be some other reason why we hadn't played the run as well, but it's not the [wide-]nine technique," Washburn said. "That might be the last thing. I won't go into it any more than that."
Still, the Eagles led at the start of the fourth quarter in eight of their first nine games. This defense was supposed to be built to maintain leads with teams forced to throw from behind. But defensive coordinator Juan Castillo's unit blew five of those leads.
The effectiveness of the wide nine, however, was on display last week at Miami as the trailing Dolphins were forced to pass. The Eagles racked up nine sacks, with Babin registering three to reach 15 for the season.
And with Babin reaching that number with three games to go, it's hard not to consider him a successful free-agent signing.
"Somebody said, 'Is he the best you ever had?' " Washburn said. "And I said, 'No, he's just a really good player.' "