Robert Saleh oversaw a San Francisco 49ers defense that came within minutes of winning the Super Bowl last year and that managed to rank among the league’s best this season despite missing many of its top players.

But that is not why the Jets coveted him.

After one of the worst seasons in franchise history, a 2-14 fiasco that exposed a lack of comprehensive oversight and resulted in Adam Gase’s dismissal after two years on the job, the Jets did not focus on finding an offensive mastermind or a defensive wizard when they searched for Gase’s replacement. They wanted a leader, an expert communicator, an energetic motivator capable of inspiring both the locker room and a fan base that had been growing more disgruntled by the day.

An extensive process led the Jets to Saleh, who after twice interviewing with the team agreed late Thursday night to become their next head coach, the climax of his 20-year odyssey from a low-level position in the business world to the leadership of an N.F.L. team.

Saleh, 41, who is of Lebanese descent, is believed to be the league’s first Muslim Arab American head coach. He spent 16 seasons as an N.F.L. assistant, the last four as the defensive coordinator with San Francisco, where players and fellow coaches alike expected him to get a head-coaching job someday.

“When you’re looking for a head coach who can establish a culture and get the respect of his players and is just a great teacher, that’s Saleh,” the former N.F.L. linebacker Brock Coyle, who played two seasons for Saleh in San Francisco, said Friday in a telephone interview. “Every time I left a meeting with him, I knew exactly what needed to be done, whether it was in practice or the game.”

The Jets have struggled to establish much of anything over the past decade except dysfunction and despair, winning the third-fewest games in the N.F.L. since their last playoff appearance, in the 2010 season. Saleh provides a welcomed infusion of dynamism.

With his shaved head and muscular physique, Saleh, a former tight end at Northern Michigan, cuts a commanding figure, and his demonstrative sideline presence — yelling, fist-pumping, high-fiving — after big defensive plays earned him sustained airtime during 49ers broadcasts.

Off the field, Saleh projects a calm and collected demeanor, Coyle said, and in the high-stress world of coaching, that resonated with his players.

“He really put critical thinking into his coaching,” Coyle said. “He’s not this ego-driven guy. He really thought about what’s the best way to relay the message he wanted to his player and always wanted to hear what the players thought. His door was always open.”

After a ragged first two seasons under Saleh’s watch, the 49ers’ defense, fueled by an influx of talent, powered the team to the Super Bowl, which San Francisco lost to Kansas City. Impressed, the Browns interviewed him in the last off-season, and after learning that Cleveland would be hiring Kevin Stefanski instead, the 49ers’ head coach, Kyle Shanahan, said: “Every year we keep him we’ll be very fortunate. Saleh’s going to be a head coach in this league. He could’ve been one this year. Most likely, he’ll be one next year.”

Several vital members from the 49ers’ 2019 defense, including Nick Bosa, Richard Sherman and Dee Ford, missed most of this season with injuries, but the team still finished fourth in passing yards allowed and fifth in total yards allowed per game.

As Saleh sets about assembling a team to his specifications, it’s likely that he will import players and coaches from San Francisco. That group could include Mike LaFleur — the younger brother of Packers Coach Matt LaFleur, who was the best man at Saleh’s wedding — as the Jets’ offensive coordinator.

If so, LaFleur would surely borrow Shanahan’s run-heavy scheme, loaded with motions and shifts, a decision that could influence how the Jets approach the quarterback position this off-season. The incumbent, Sam Darnold, played in a version of that scheme as a rookie, but the Jets must decide whether to continue building around Darnold or to trade him, filling his spot with a veteran or a first-round pick, perhaps Justin Fields of Ohio State or Zach Wilson of Brigham Young.

Saleh grew up in Dearborn, Mich., home to one of the country’s largest Arab American communities, and after graduating from Northern Michigan in 2001, picked finance over football, going to work for Comerica Bank. But a few months later, when his brother David escaped the South Tower during the terrorist attacks of Sept. 11, Saleh reassessed what he wanted from life.

“His love and passion for football is ultimately why he wanted to get into coaching,” David Saleh told The Detroit News in 2020. “He just didn’t want to leave the game.”

Saleh worked for three college programs over the next four years before joining the Houston Texans as a defensive intern in 2005, a move that altered the trajectory of his career. There, he met Shanahan, who would hire him in 2017 as the 49ers defensive coordinator.

Saleh became the fourth head coach of color currently in the N.F.L., according to the league’s measures of diversity, with four openings still to be filled. His hiring came several months after the league updated the Rooney Rule, which aims to increase diversity in candidacies for head coaching jobs and certain front office roles. The rule was changed in May to bump up its interviewing requirement from at least one external minority candidate for each head coaching position to at least two.

When Jets General Manager Joe Douglas recently delineated his ideal qualities for the next coach, he only alluded to football. He mentioned character, integrity and communication skills. After interviewing nine candidates, after listening to their plans and their visions and their ambitions, Douglas and the Jets knew what they needed.

They needed Robert Saleh.