Relax, Eagles fans. HBO’s ‘Hard Knocks’ is making the Lions look better than they are.

As Philip Seymour Hoffman said in Almost Famous, here’s a theory for you to disregard: I’m betting there are more than a few of Eagles fans who are worried, or at least concerned, about the team’s season opener Sunday in Detroit against the Lions, and the reason they’re worried isn’t the Lions’ talent, or the Lions’ coaching, or the Lions’ offensive and defensive schemes and strategy. The reason they’re worried is a TV show.

That TV show, of course, is Hard Knocks, on HBO. The Lions were the 18th team to participate in the long-running documentary about life during NFL training camp and preseason. As usual, the series dramatized the mundane and unearthed some insights into how players think, how coaches coach, and how these people act and interact while dealing with the pressures of performing at pro football’s highest level.

If you think Eagles coach Nick Sirianni comes up with some head-scratching analogies, for instance, you should listen to the Lions’ Dan Campbell compare the NFL to an ocean: “There’s a number of teams that barely get to the water,” he told his team, “and there are a number of teams in the shallows, man, and they are all over your ass, and they strike and move.” The metaphor was so tortured that, as soon as Campbell uttered it, the United Nations launched an investigation of him.

Little moments like that one are what make Hard Knocks fun to watch. But during a conference call Wednesday, Campbell didn’t sound particularly enthusiastic about the whole experience. Asked if he had any hesitation about participating in the show, he said, “Listen, we did what we were asked to do, and we made the most of it.” No one should be surprised that Campbell was less than sanguine about having cameras tracking him and his team for several weeks. Most NFL coaches abhor such “distractions” and are paranoid that even the most irrelevant of details will breach the walls of their compound and land in the game plans of their upcoming opponents.

“We watch everything,” Sirianni said. “We are going to listen to media broadcasts of what the Lions do. You are doing everything you can do to turn over every single stone you can turn over to see if you can get an advantage. The parity in this league is so tight and so small, and the margin of error is so small.

“Of course, you try to take anything you can from anything. We’ll watch Coach Campbell’s press conferences. We’ll watch Jared Goff’s press conferences, and sure we’ll watch Hard Knocks to figure out if we can get something out of it.”

Campbell may have disliked appearing on the show, but the gaga-for-pigskin viewing audience surely loved it, in large part because Hard Knocks provides something that fans don’t often get: an intimate look, or the perception of an intimate look, at the inner workings of an NFL organization. Campbell himself came off well, as a young coach with an old-school mindset who has the Lions hit and tackle more during camp than the average team nowadays does, who relies on classic challenge-your-toughness rhetoric to motivate his players.

“He said some things that made me want to run through brick walls,” Eagles center Jason Kelce said.

If a hardened vet such as Kelce reacted that way to Campbell and the Lions, the impact on casual fans must have been even more profound. That’s the magic of the doc: It gives congregants in the church of football a glimpse inside the sanctum, and it’s easy to get swept up in the combination of romance and realism that Hard Knocks delivers.

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Of course the Lions look like a decent team. Of course they look like a threat to beat the Eagles. Of course fans around here will draw conclusions about the Lions based on the show — conclusions that they can’t draw about the Eagles because the Eagles aren’t getting the same big-time TV/streaming treatment at the moment — and some of those conclusions will be along the lines of, Whoa, this team seems pretty tough. The Eagles are in for it Sunday. HBO isn’t in the business of making the centerpiece of one of its signature series look boring or incompetent, even if that team went 3-13 last season and still starts Goff at quarterback. Such is the effect of the three Es of television: excess, embellishment, editing.

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“There are cameras around,” Kelce said. “They want guys being who they are, but they act because they want to be popular on a TV show. I think that’s one of the downfalls of having stuff like that in the building. It leads away from the authenticity of who people are.”

“Hopefully, they didn’t have to have too many retakes,” defensive end Brandon Graham said. “I know it’s all about putting out good content.”

Just remember what Graham, Kelce, Campbell, and the rest of the Eagles and Lions already know: Sunday, 1 p.m., Ford Field. That’s the content that counts. Not a five-episode think piece on a mid-level team struggling with its own limitations in the harsh face of the NFC North.

Inquirer Eagles beat reporters EJ Smith and Josh Tolentino preview the team’s season opener against the Detroit Lions. Watch at Inquirer.com/EaglesGameday