The line, said linebacker Jamar Chaney, is expected to get pressure nearly every play, "so the linebackers [can play] downhill."
The acquisition of defensive end Jason Babin is aimed at helping create that pressure and taking some of the workload and double teams off of Trent Cole.
"It's awesome," Cole said. "We're having fun, and that's what it's supposed to be like."
While the line pressures, the Eagles envision cornerback Dominique Rodgers-Cromartie helping to shut down receivers.
"You want guys who can cover both sides," Howie Roseman said. The general manager said he tries to fit all the pieces together when making personnel decisions. "There's a lot of moving parts."
The new parts are on the sideline, too, as the Eagles revamp a defense that finished 21st in points allowed last season, including a historically dismal performance in the red zone. The Eagles pressure faded as the season wore on - they had 15 sacks in the last eight games after getting 24 in the first eight - and they couldn't find a solid partner for Asante Samuel.
Castillo, whose only coordinator experience was at Kingsville High School in Texas, is coaching defense for the first time in more than 20 years and bringing his trademark intensity to the job. Much as he did for years as the Eagles offensive line coach, on Thursday Castillo chased his players downfield, smacking them on the helmets even after noncontact plays.
"A lot more excitement," Tapp said.
The new position coaches are led by defensive line coach Jim Washburn, a salty and revered guru who in Tennessee helped turn Babin from a journeyman to a Pro Bowl player.
"Players respect him. Good bad or indifferent, he's going to tell you what he feels and what he sees," Tapp said.
Of course it's easy to be optimistic and to praise your coaches after the first day of practice. The real test isn't until Sept. 11.
And in the players' praise for Castillo and Washburn, it's easy to read thinly veiled criticism of departed coordinator Sean McDermott. Players chafed under his intense style and constant defensive tweaks.
The Eagles are giving Castillo the benefit of improved personnel, with Babin and Rodgers-Cromartie the highlights so far.
But the inexperienced coordinator also has an inexperienced team. Gone is safety Quintin Mikell, an eight-year veteran who led the defensive backfield.
In his place are second-year men Nate Allen and Kurt Coleman and rookie Jaiquawn Jarrett. Neither Allen nor Coleman has started a full 16 games, but each has said he expects to become a leader.
'A little intimidating'
Likely gone is linebacker Stewart Bradley, the quarterback of last year's defense. In his place Thursday was Matthews, a fourth-round draft pick known for his football smarts.
"At first it was a little intimidating, but I got used to it," said Matthews, who made play calls and directed veterans in his first NFL practice. He said he believes he can start as a rookie.
Roseman said he's not done making moves, so it will be interesting to see if the team brings in a veteran to lead the way or trusts Matthews enough to head into Week 1 with him calling plays.
Chaney, meanwhile, went from middle linebacker last season to strong-side linebacker Thursday, with Moise Fokou switching from the strong side to the weak side.
Among the many moves, those were two small shifts on a defense hoping that new faces can lead to a drastic change in results.
Contact staff writer Jonathan Tamari at 215-854-5214, firstname.lastname@example.org, or @JonathanTamari on Twitter.