The Eagles and Chargers may on the surface inhabit disparate worlds in the NFL, but the separation between the teams from different coasts and different conferences narrowed in degrees following their coaching searches last offseason.

New Eagles coach Nick Sirianni spent five formative years with the Chargers. And during that span, he coached alongside Shane Steichen, whom he hired as offensive coordinator.

Steichen stayed in Los Angeles until last season, but new coach Brandon Staley brought in his own staff, which likely influenced Steichen’s move to the Eagles.

Staley was scheduled to interview before Sirianni, but he accepted the Chargers’ offer and canceled his meeting with the Eagles.

And both coaches had targeted the same defensive coordinator. Staley had known Jonathan Gannon since they were children, and Sirianni had worked with him in Indianapolis. But for various reasons Gannon chose the Eagles over the Chargers — among other teams.

While Staley has gotten off to a better start than Sirianni, and seemingly the Eagles’ coordinators, it’s too early to draw conclusions about which team did better. But Sunday’s meeting between the 3-5 Eagles and 4-3 Chargers does offer the opportunity to re-examine the process behind the hiring of Sirianni and his staff.

And it also provides the chance to explore how significant his and Steichen’s experiences in San Diego and L.A. were to their offensive philosophies.

“Obviously that was a big development part in my coaching,” Sirianni said. “Also being around a player like Philip Rivers. You got to come with your ‘A’ game as a coach every single day because there [are] not too many things that that guy hasn’t seen.

“When I became the quarterback coach there, I had to dig and claw and scratch to give him a nugget that he might not have seen, because, again, this guy would see everything.”

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Steichen, who succeeded Sirianni as quarterbacks coach, had much the same to say about the recently retired Rivers. Both often name-check him, not only because of his accomplishments but also because he was the most prominent quarterback in their coaching careers.

“Philip Rivers was a coach,” Steichen said Tuesday. “When you have those conversations in the quarterback room day-in, day-out and on the field, he sees the game so well. When you’re talking to him, he had like a picture-[perfect] memory.”

Both coaches had their successes with Rivers, but there were also occasional lean years. Steichen left for the Colts last season and teamed up again with former Chargers offensive coordinator Frank Reich and Sirianni, and they made the playoffs.

Steichen stayed with the Chargers, was promoted to offensive coordinator, and was handed the keys to talented rookie quarterback Justin Herbert. But the team still struggled, and coach Anthony Lynn was fired and Steichen subsequently left.

Sirianni and Steichen had remained close after the former left for Indy in 2018. While there were questions about the relative youth of Sirianni’s staff, and that he didn’t hire an assistant with head coaching experience, little was made initially of their re-pairing.

The coach would call plays and Steichen, who had a season-plus of play-calling under his belt, would be his right-hand man. And they would speak the same language, having worked in essentially the same system.

But neither had much experience working with a mobile quarterback such as Jalen Hurts and the zone-read-based elements they would eventually install to account for his strengths.

Asked if hiring Steichen gave him pause because they came from similar backgrounds, Sirianni noted their three seasons apart when he had left for Indy to work for Reich, who had two years away from the Rivers offense with former coach Doug Pederson and the Eagles.

“Our offense evolved there in Indianapolis to look — I don’t want to say completely different, but to look different than it did in San Diego,” Sirianni said Monday. “That’s my same thought here. Shane went … [and] did the same thing when I left.”

But the Eagles offense so far has often looked disjointed with Sirianni and Steichen seemingly uncomfortable implementing the college half and Hurts uncomfortable executing the pro-style half. There have been positive stretches, most notably last Sunday in the Eagles’ 44-6 win over the hapless Lions.

But the offense has lacked a consistent identity or one seemingly built with a particular quarterback in mind.

Herbert set numerous rookie passing records last season, so Steichen must have done something right. The coordinator had a few dubious calls in late-game situations, but he also had an offensive-minded boss, so it’s difficult to decipher responsibility.

Staley could have retained Steichen, but most new coaches have specific coordinators in mind. Joe Lombardi was his choice, and while Herbert got off to a hot start, he cooled the last two weeks.

When the Eagles opened their search for Pederson’s replacement in January, they had a list of 25 candidates. They ultimately interviewed only 10, but Staley was the only coach to reportedly not follow through on a scheduled meeting.

The then-Rams defensive coordinator interviewed with the Chargers first, doing so both virtually and in-person. He also spoke virtually with the Texans. But on the day before he was to fly to meet with the Eagles, he accepted the Chargers’ offer.

The 38-year-old Staley wouldn’t have to move for his next job, but Herbert clearly factored into his decision. He also didn’t go through with the Eagles interview partly because of the dynamic in Philadelphia, with general manager Howie Roseman surviving three coaching firings, two NFL sources said.

The Eagles still had Carson Wentz, but he had just come off one of the worst regressive seasons for a starting quarterback. Wentz, Pederson, and the overall dysfunction of the team played roles in his decline, but Roseman’s drafting of Hurts helped set the ball in motion.

Roseman eventually traded Wentz to the Colts and salvaged a conditional second-round draft pick that is on course to become a first-rounder. He had also yet to make a predraft trade that secured the Eagles another 2022 first-rounder.

But the Eagles, who also had an aging, expensive roster, were not an attractive destination at the time of their coaching search. Arthur Smith was one of their first interviewees, but he eventually took the Falcons job.

Of the other early interviewees, Patriots offensive coordinator Josh McDaniel emerged as a favorite. There were obvious reasons for the Eagles to have cold feet. He had a brief, unsuccessful first stint as coach a decade ago with the Broncos, and he had infamously reneged on the Colts in 2018.

McDaniels, who has since overseen Patriots quarterback Mac Jones’ solid first season, would also potentially upend the status quo. He would have sought to remake much of the Eagles operation and that could have threatened the connection owner Jeffrey Lurie had with his team and Roseman’s place in that association.

McDaniels’ broken pledge, interestingly enough, paved the way for Reich, who would be perhaps Sirianni’s greatest advocate. He also put Gannon on the Eagles’ radar, having identified the then-Colts defensive backs coach as his defensive coordinator choice, sources close to the situation said.

Sirianni interviewed with the Eagles the day after Staley would have flown to Lurie’s West Palm Beach, Fla., home. They met for almost 12 hours over two days, and he offered desired choices for his assistants with Gannon as his ideal defensive leader.

The Chargers, meanwhile, interviewed Gannon. He first met Staley when they were 10-year-olds competing in AAU basketball tournaments in the Cleveland area. They reconnected as they got into coaching, and Gannon had once suggested Staley for an opening at Division III John Carroll.

“You’ve got to know somebody to show somebody,” Gannon said. “So, I got him in the door … and the rest was history. I don’t take any credit for [Carroll’s] hiring him because he did that all himself.

“But we’re friends. We’re good friends and we talk. I learned a lot of ball from him, and hopefully he’s learned some ball from me.”

Sirianni offered a better opportunity, though, as Gannon would be able to call plays for an offensive-minded coach. He had other reasons for choosing Philly, but the Eagles had snagged one of the more sought-after young assistants, even if he had no coordinator experience.

Gannon has taken his lumps, but he has also had more sustained moments than Sirianni. An impressive showing against Staley, Herbert, and the Chargers wouldn’t exactly justify his hiring, but it could be a feather in the cap.

The rest of Sirianni’s staff was made up assistants he took from the Colts (pass game analyst Kevin Patullo and tight ends coach Jason Michael), holdovers from the Eagles (offensive line coach Jeff Stoutland and receivers coach Aaron Moorehead), and others assembled through scouting and interviews.

Roseman aided the search and put special-teams coordinator Michael Clay and quarterbacks coach Brian Johnson on his radar, but Sirianni made the final calls.

Lurie and Roseman had influenced some of Pederson’s coaching decisions, partly out of necessity, but it’s hard to dispute the notion that they allowed Sirianni say over his first staff.

It is the youngest in the NFL, and that a first-time coach would forgo having a veteran who stood in his shoes was in contrast to the Eagles’ two previous first-timers. Chip Kelly had Pat Shurmur, and Pederson had Jim Schwartz.

“I have great people that I can talk to,” Sirianni said last week. “There’s no secret … I go through a rough patch, I talk to Frank. My dad’s been a coach forever, I talk to him. My brother’s been a coach forever, I talk to him.

“[Raiders defensive coordinator] Gus Bradley’s been a coach, I get to talk to him.”

But they aren’t in the building.

“They’re not in the building, you’re right,” Sirianni said. “But I can call them when I need to call them and be able to talk through things with them when I need to talk through things with them.

“I’m very confident in that. I’m very confident in the people I have in my corner.”

But the rest of the season could dictate if offseason coaching changes are in order or ordered. Lurie and Roseman, for instance, had wanted Reich gone after Pederson’s first year. He held firm, and the Eagles went on to win a Super Bowl.

That would be a best-case-scenario second season for Sirianni. But right now the Eagles seem as far from a title as they do the Chargers.