Especially active was nose tackle Bennie Logan, who spent more time on the other side of the line of scrimmage than he did his own.
Logan and starting defensive ends Fletcher Cox and Cedric Thornton set the tone for their backups as well, and the Eagles held the Colts to just 281 yards despite the Colts finishing with a 36:14 to 23:46 advantage in time of possession.
"I feel like we respect and trust each other," Cox said. "I think that goes back to Square 1. We respect and trust each other and believe in each other. We know that we're going to get the job done no matter what the situation is."
When Logan exited, it was Beau Allen's turn to masterfully clog the middle, which he did until the staff wanted to see what Wade Keliikipi and Travis Raciti could do. That's when Allen moved outside to end, where rookie Brian Mihalik made himself noticed with three tackles and the team's only sack.
Although the Colts finished with 132 rushing yards, they needed 37 attempts to get them. Those are the kind of numbers the Eagles will take every week of the season, especially if their pass defense plays like it did on this day, limiting the Colts to 17 completions in 39 attempts for 150 yards while getting two interceptions.
"As long as we can stop the run first, and most good defenses do that first," defensive coordinator Billy Davis said, "that's the foundation of a good defense. We have a good group of second-year D-linemen and a good crop of young guys that played well today. As long as they continue to develop like that, we'll be pretty solid."
Perhaps most encouraging was the way many of the Eagles' rookies played.
First-round pick Nelson Agholor caught three passes for 57 yards, including a 34-yard burst to the end zone for his first pro score.
Second-round pick Eric Rowe forced a fumble and finished with three tackles.
Third-round pick Jordan Hicks threw a big block to help spring Kenjon Barner for a 92-yard punt return.
Sixth-round pick Randall Evans had a tackle for loss and a fumble recovery that set up the final touchdown.
Seventh-round pick Brian Mihalik had three tackles and a sack.
The only draft pick this year who didn't do something positive in this contest was cornerback JaCorey Shepherd, who's on the injured reserve list after tearing an ACL.
But it wasn't just the draft picks who played well. Wide receiver Rasheed Bailey caught a pair of passes and tight end Eric Tomlinson led the team with five catches.
"The one thing you don't know about any of those guys is what they're going to be like [when] you get them into a game, and that's the encouraging thing," coach Chip Kelly said. "Sometimes the guys stand out in practice … and then all of a sudden you get in the game and they are not the same player, and then other guys that were not so good standing out in practice stand out in the game.
"We're excited about those guys," Kelly said. "It's just one step for us, but we feel like we've got a lot of really good film to teach off of with officials, legitimate down and distance, all those things; a lot of good situations that we can get in the meeting room with those guys when they come back on Tuesday and really start to grow this team."
Not every Eagle had his best day on Sunday.
Kicker Cody Parkey missed on an extra point and a field-goal attempt from 34 yards.
Safety Jaylen Watkins was one of three players to miss a tackle of Josh Robinson on a 9-yard touchdown run, and Darren Sproles dropped the only pass thrown his way before departing early along with the rest of the starters.
Despite the misses, Parkey insists his confidence is "sky high, couldn't be better. We have the best holder [punter Donnie Jones], the best [long] snapper [Jon Dorenbos] in the league, the best protection. I just have to go out there and kick and do my thing."
The last word
"All I know is that Nelson [Agholor] balled today. I'm proud of him. He makes it look easy. Like I said, when you practice fast and you're as fast as he is, the game is going to slow down a lot quicker. Then, on top of his natural ability, he works extremely hard and he's smart. I think this game is going to come easy for him. He's going to come into his own quickly. I think he's going to help this offense a lot. — Eagles WR Jordan Matthews, on rookie and fellow WR Nelson Agholor.