Lane Johnson has played every one of the Eagles' offensive snaps this season, all 947.

He is not the only player on the offensive line, let alone on the team, to do this. Jason Kelce, the center, has done it. Allen Barbre, the left guard, has done it. But because Jason Peters has missed two entire games and parts of three others with various injuries, Johnson has had it a little harder than either Kelce or Barbre.

He has ricocheted from right tackle to left tackle and back again. Those are the two most important positions on the line, of course, and they present different challenges and require a player to employ different techniques to perform competently. And Johnson has been very good at handling those challenges and employing those techniques despite straining his left medial collateral ligament, spraining his left ankle, and spraining the AC joint in his left shoulder. He will be on the field again Sunday against the Arizona Cardinals, this time at right tackle - for the entire game, he hopes. If you can find someone who has been more valuable to the Eagles this season with less fanfare, you are free to try.

"It's part of the job description," Johnson was saying Thursday after practice. "It's a [lousy] job. As far as payment, payment is among the best, as far as tackle. But it really is a [lousy] job. Nobody knows your name unless you mess up. It's just part of the job description.

"I've heard stories of Jon Runyan when he went and cracked his tailbone in the cold tub and had to get a shot in his ass before he had to play every game. You just learn from guys like him. He kind of set the tempo for what it's like here."

Johnson hears those stories about Runyan from Chris Peduzzi, who spent 14 years on the Eagles' training staff before becoming the team's head trainer in 2013.

"He was a tough dude," Johnson said of Runyan, and there is a broader connection between them. Runyan was the first major free-agent signing during Andy Reid's tenure as head coach. After one year here, Reid understood the Eagles needed a right tackle. They homed in on Runyan; signed him in February 2000 to a six-year, $30 million deal; and for the next nine seasons never had to worry about the position.

Johnson was Chip Kelly's first draft pick, the fourth overall selection in 2013, having played at Oklahoma. The only four games he has missed over his three seasons with the Eagles were because of a suspension for violating the NFL's policy on performance-enhancing substances. He said at the time that he had failed to alert the Eagles' training staff that he was taking a prescribed medication banned by the NFL. He said Thursday that his mistake is one of the reasons he doesn't want to come off the field despite the strains and sprains, that he doesn't want to let his teammates down now like he did then.

"There's a difference between being hurt and being injured," he said. "Injured is when you obviously can't go. Especially this time of year, this is crunch time. This is when your team needs you most. You have a couple of weeks of pain, but you have a long offseason to recover."

He is 25 years old, 6-foot-6, and 317 pounds, and he was asked whether he gives any thought to the health problems that might await him years after he has stopped playing. He chuckled at the question. "I'll probably be in a wheelchair," he said with a smirk, before turning serious.

"I take care of myself recovery-wise," he said. "So after football's over, in retirement, I'm not going to be too banged up. That's probably the biggest thing, is taking care of myself now. My rookie year, I didn't really do nothing. It got toward the end of the year - you play your senior year, go to the combine, and you're just dog tired. I didn't really know how to be a pro, to take your body seriously, because in college you're just having fun playing. You don't really take it seriously. Now, I'm just trying to prevent things, with stretching, with stuff that can help you to where injuries don't happen.

"They expect things. You're a first-rounder. You need to go out there and perform."

So he will line up Sunday, get in his stance, put his hand in the dirt and the pain out of his mind, and steel himself to deliver and withstand more punishment in the tiny moments of violence we see and forget about every week. And then he will do it again, and again, and no one will say a word unless he screws up. It is the toughest part of his (lousy) job, that contrast between silence and sound. But Lane Johnson knows how it goes. After all, people expect things.