The most vocal member of the line is center Jason Kelce, who is the leader of the group in his third NFL season. A former sixth-round pick, Kelce has become one of the team's most indispensable players.
The "little brother," as he calls himself, is rookie right tackle Lane Johnson. As the No. 4 overall pick in the NFL draft, Johnson arrived with the onus of expectations and the fortune of joining a group with chemistry - even if the members were apart last season.
They are overseen by line coach Jeff Stoutland, a self-labeled "pig head" who arrived in Philadelphia without NFL experience and earned the respect of his linemen despite succeeding two established line coaches.
Of all the differences between last year's team and this year's, the health and stability of the offensive line are among the biggest. The Eagles quintet has played 667 of the Eagles' 751 offensive plays this season and started all 11 games. LeSean McCoy has already topped 1,000 yards rushing behind the group, and quarterback Nick Foles has often benefited from a clean pocket during his surging stretch.
"Continuity is one thing, but continuity with talent is the most important thing," Mathis said. "Because we have five very good players out there. If we had five terrible players out there who were out there the whole year, it wouldn't yield the same results."
Benefit of stability
In 2012, the Eagles started five offensive line combinations. Nine linemen started games. The Eagles signed a player off the street on Monday and started him the following Sunday.
Mathis was the only lineman who lasted the season. Peters missed the entire year after twice rupturing his right Achilles tendon last offseason. Kelce missed almost the entire season after tearing knee ligaments in Week 2. Herremans lasted eight games before a dislocated bone in his foot and ligament damage cost him his season.
They all returned and have avoided injuries related to 2012. That stability has been critical.
"It's unbelievable how important it is to have the same five guys there communicating," Stoutland said. "Most mistakes are because of communication, not because a guy gets beat."
The communication starts with Kelce. Former Eagles coach Andy Reid compared playing center to the "changing sands of Cape Cod." Teams build their lines from the outside in, but the game is played from the inside out. Kelce gives the signals and makes the adjustments for the players around him.
One breakdown on the line could disrupt the whole play. Herremans echoed Stoutland, insisting that the biggest issues with the line this year have come from communication issues.
"We aren't really five different positions; we're basically one position," Herremans said. "That's why they call it a unit."
Kelce and Kelly both noted that stability is more important on the line than other positions for that reason. When a new player must fill in, the adjustment requires time. Peters exited a Nov. 13 win over Green Bay with a quadriceps injury, and the coaching staff was pleased with the way Allen Barbre filled in because of the difficulty of that task.
"The more and the more you get to play with someone - not just in a season, but years playing with guys - that really helps," Kelce said. "We've been lucky so far this year."
Importance of Peters
The player most often on the injury report this season is Peters. A five-time Pro Bowler, he has dealt with three ailments. He always insisted that he would play, and said the injuries would not be a big deal if the league did not mandate a public injury report.
The closest Peters came to missing a game was the Nov. 17 win over Washington, when he was a gametime decision after a week of being limited in practice. Peters took every offensive snap in the game and said the missed time in practice didn't disrupt him.
"I know exactly what to do and how to do it," Peters said. "It's almost mechanical."
The same could be same about Peters' season. He insisted during the offseason that last season's injury would not bother him in 2013. There was skepticism because a player at his size (328 pounds) and his age (31) with his athleticism recovering from that injury is unprecedented.
Peters didn't understand the public's concern. He is now a potential candidate for comeback player of the year.
Stoutland marveled at how Peters takes on the opponent's best player each week. The website Pro Football Focus has tallied just two sacks allowed and two quarterback hits allowed against him. They grade his pass blocking superior to his run blocking.
Stoutland, who used to show his college players film of Peters as the prototypical tackle, said he could freeze-frame the film this season to demonstrate how astounding it is for a player Peters' size to crouch so low on defenders.
"I can't count too many times I'm playing as good as I'm playing now," Peters said.
Buying into coach
Stoutland succeeded Juan Castillo and Howard Mudd, two offensive line coaches with a list of Pro Bowlers on their resumés. Stoutland, a former college assistant, was never in the NFL.
Stoutland said he had confidence in his coaching and knowledge, but he needed the seasoned veterans to buy in.
"We would be selling ourselves short if we didn't buy in," Mathis said. "You have to hear the guy out, listen to the guy. And Stout's the kind of guy who would listen to us, too."
Stoutland said he became more analytical in the NFL. In college, he focused on elemental aspects of the position, as well as off-the-field aspects such as how to prepare during the week.
There are times in meetings when he might say something too obvious. Herremans will give him a look to show that the linemen already know. The players appreciate the give-and-take permitted, and Herremans said the veterans know there are points that need to be made so younger players can hear them.
"He didn't come in here and try to drastically change the way anybody did things," Mathis said. "You don't come in and change Jason Peters' pass set, you know? But that doesn't mean he's not coachable."
Stoutland emphasized understanding the players' families and backgrounds. He thinks that goes a long way. But ultimately, the players respect acumen. Peters said he used to have meeting rooms that included breaks. Not the one here.
"He doesn't stop coaching," Peters said. "You bump into him at lunch, he's coaching. You bump into him in the hallway, he's coaching."
Sign of success
At one point in the Green Bay game, Mathis saw the NFL's rushing leaders on Lambeau Field's scoreboard. McCoy was No. 3. At the end of the game, McCoy was back at No. 1. Mathis made sure.
Peters said in training camp that he expected McCoy to reach 1,000 yards by Week 10. Eyebrows were raised at the comment. McCoy did it in Week 11, the first in the NFL to reach that mark. Johnson said the linemen are resolute about McCoy's finishing the season as the leading rusher.
There isn't a metric to show if, or how well, the line performs. The members look at McCoy's rushing yards or how clean Foles' jersey appears at the final whistle. Kelce said they put most of the weight on the grades from coaches. Mathis said a lineman knows when a statistic is misleading, and can tell how many assignments he fulfilled.
The most telling evidence, though, is the production of the offense. The line has been stable this season and the offense has been one of the best in the NFL. They don't think it's a coincidence.
"The production of the offense, a lot of that relies on the offensive line," Herremans said. "We have a productive offensive line, not just in stats, but in situations."