SANTA CLARA, Calif. -- In an offseason of major moves involving the San Francisco 49ers, the biggest departure wasn't a player. It was defensive coordinator Robert Saleh, who left after four seasons to become the head coach of the New York Jets.

While Saleh's loss had been expected, it was no less significant. Replacing Saleh, who led the 49ers defense to DVOA ranks of second (2019) and sixth (2020), is no easy task. How well the Niners did in replacing Saleh will go a long way in determining whether they can surge back into contention in 2021.

Although older, more established defensive coaches such as Dan Quinn, Gus Bradley and Raheem Morris were available, San Francisco coach Kyle Shanahan had his replacement choice in-house the whole time. Shanahan promoted DeMeco Ryans -- the type of young, intelligent, enthusiastic coach Saleh was when he got his first chance to run a defense in 2017 -- from inside linebackers coach to defensive coordinator on Jan. 18.

Since, Ryans has made it clear to his players he isn't going to try to emulate Saleh, though he's happy to apply many of the things he learned from Saleh in their four seasons working together.

"I am my own person and Saleh has taught me a lot," Ryans said. "He's probably one of the coaches who has taught me the most football that I've been around. He's been very integral to my development as a coach and I can't thank him enough for all of the things that he's instilled in me. There will be some of the similar, you know, scheme things that we've done in the past ... but you will see some wrinkles. You will see some wrinkles, you will see my brand of football on it."

It's not hard to figure out what Ryans might bring to the 49ers defense even as a first-time coordinator. Asked last week what his "brand" might entail, Ryans quickly threw out words like "fast," "physical" and "aggressive," mentioning an attacking defensive line, a back seven that focuses on fundamentals and feeds off of what the front four does.

That mindset is undoubtedly an extension of Ryans' own playing career but also not much different than what the Niners did under Saleh. A former second-round pick of the Houston Texans in 2006, Ryans spent 10 seasons playing middle linebacker, earning Defensive Rookie of the Year, a first-team All-Pro nod in 2007 and two Pro Bowl appearances.

His playing résumé instantly earned Ryans plenty of credit with his players when he joined Shanahan's staff as defensive quality control coach in 2017.

"He knows what it takes as a defensive player, he knows what it takes in the league," cornerback Jason Verrett said. "He's done a hell of a job getting the guys up front going, it all starts upfront and then it ends on the back end. So, it's been fun so far being out there with a guy who has played in the league and knows a lot about the ins and outs of football so it's been very relatable for us."

The adjustment for Ryans hasn't been so much about relating to players as it has been keeping his focus on a bigger picture. Where he once spent his time only around inside linebackers, he now has to make sure he gets time with the defensive line and secondary as well.

Free safety Jimmie Ward said Ryans is also working on making things "way more simple" for the players in terms of the calls.

"He listens to what the players have to say and he adapts to it," defensive end Samson Ebukam said. "At the same time, he's got a controlling voice. Everybody respects him in the room and we know that he's looking out for our best interest. He's putting us in the best situation to be successful."

As for how Ryans compares to Saleh on game days, that remains to be seen. Ryans says he will call the plays from the sideline, same as Saleh, who became the favorite of television broadcasts for some of his antics after his players made big plays. Ryans can't promise he will have similar "Hulk" reactions but he also won't be afraid to show his enthusiasm.

And though stepping into Saleh's big shoes is no easy task, Ryans believes any pressure on him can be alleviated by the work he puts in.

"There's no pressure, but it's just, have you prepared yourself for the moment?" Ryans said. "I think for me, it's just putting in the work now in the offseason, putting in work during the season."

The comparisons to Saleh are inevitable, especially if and when there are defensive hiccups. But while Saleh's contributions won't soon be forgotten by the Niners or Ryans, all that really matters is what happens next.

"Saleh, love him, great coach, but he's on the Jets now," Ward said. "I wish him the best, but at the end of the day, I'm gold and red over here. So I'm team 'Meco. Whatever 'Meco says, I'm rolling with him."