SANTA CLARA, Calif. -- For the fourth time in his tenure as San Francisco 49ers coach, Kyle Shanahan is looking for a defensive coordinator.
Unlike the previous three searches, this one is a result of a job vacancy that Shanahan himself created. On Feb. 14, he announced that the team was parting ways with coordinator Steve Wilks after one season. It was a departure from losing previous coordinators Robert Saleh and DeMeco Ryans to head-coaching jobs with the New York Jets and Houston Texans, respectively.
Upon revealing that decision, Shanahan noted that hiring Wilks from the outside and asking him to adapt to a defensive system already in place made for an awkward match, one that ultimately didn't work out.
"That was the hardest part," Shanahan said. "I knew that was a challenge. It was tough. ... Bringing in Steve, he was unbelievable and how loyal he was and him trying to do it, but it just ended up not being the right fit."
What Shanahan and the Niners now must do is find a coordinator who does fit. Because San Francisco advanced to Super Bowl LVIII, every other defensive coordinator opening had already been filled, with many top potential outside candidates landing elsewhere.
While unfortunate, it also means the 49ers can take their time in determining which direction they want to go to replace Wilks.
That has been apparent in the pace of the search. As of Wednesday, the only four known candidates for the job are former Los Angeles Chargers head coach Brandon Staley, Kansas City Chiefs defensive backs coach Dave Merritt as well as in-house options Nick Sorensen (defensive passing game specialist/nickel cornerbacks) and Daniel Bullocks (defensive backs coach). All will have interviewed by the end of the week.
Among other names that have been connected to the Niners are Texans linebackers coach Chris Kiffin and Jeff Ulbrich, the Jets' defensive coordinator. Ulbrich, a San Jose native, played for the Niners from 2000-09 and worked with Shanahan on the Atlanta Falcons' coaching staff in 2015-2016. But Ulbrich remains under contract with the Jets, who would have to allow him to leave for the 49ers to hire him.
The NFL's Rooney Rule stipulates that the Niners must also interview at least two external minority candidates, with Merritt being the first candidate who satisfies that requirement.
"We're in no rush," general manager John Lynch said. "We kind of know who we are, who we're going to be, and that's not going to make a wholesale schematic change there. We feel good about where we're at."
Indeed, the Niners defensive system has, for the most part, remained the same since Shanahan and Saleh installed it in 2017. It's a 4-3 scheme that relies on the front four to generate pressure, with hefty amounts of zone coverage behind it.
Over the past seven seasons, whether it was Saleh, Ryans or Wilks in charge, the Niners played zone on 60.8% of opponent dropbacks, the highest rate in the NFL. That includes playing Cover-2 on 18.5% of dropbacks (10th-most), Cover-3 on 25.9% of dropbacks (sixth) and quarters on 14% of dropbacks (fifth).
Along with that, San Francisco has blitzed on just 23% of dropbacks, the ninth-lowest rate in the league.
While there have been tweaks over the years, most notably a switch to the "wide-9" alignment on the defensive front, the defense has retained many of its core principles. And it has worked, as the 49ers have finished in the top nine in scoring defense and defensive expected points added in four of the past five seasons.
All of which would point to the 49ers hiring someone who has been around the scheme, such as Sorensen or Bullocks, as the most likely outcome while remaining open to outside ideas.
"I'm not close-minded in any way," Shanahan said. "I'll look into every possibility. But you know when you have some good players who have played at a high level and done it a certain way, I'm not just trying to change that. I lean towards trying to keep them doing similar stuff that they've been very good at that's got us very far. But I have to make sure that I find the right person who's capable of leading our group in that way."
Beyond not having experience in the Niners' preferred defense, Wilks also was Shanahan's first defensive coordinator with a background mostly rooted in coaching defensive backs. Saleh and Ryans had previously worked with linebackers, the position group which has the most holistic view of the defense.
While cornerback Charvarius Ward had a career year and earned second-team All-Pro honors and fellow corner Deommodore Lenoir had a breakout season as the Niners tied for the league lead with 22 interceptions, the coverage and pass rush struggled to get on the same page.
"There's no one way to do things, but you want to tie things together," Shanahan said. "Steve was always working to do that. There's no doubt about that. But it was just for his background and how it ended up with us ... it was harder than it needed to be."
That doesn't mean the next coordinator must have a history of both coaching linebackers and running San Francisco's scheme, but it seems likely that at least one of those things would be important.
While Merritt works with defensive backs in Kansas City, he also played linebacker for three seasons in the NFL and coached linebackers for the Jets from 2001 to 2003. Working with Chiefs defensive coordinator Steve Spagnuolo, Merritt has been in an attacking 4-3 scheme but one that emphasizes more man coverage on the back end.
Staley has a history working with all levels of the defense, including linebackers at the NFL level. But he is also a Vic Fangio disciple, known for running a system that prefers a 3-4 front that has answers for anything an opposing offense runs but creates more complexity for the defensive players executing it.
At this week's NFL scouting combine, Lynch said those differences aren't reasons to rule out Staley, whom he called "really bright." Lynch also added that just because things didn't work out with Wilks doesn't mean the Niners would shy away from an outside replacement. If nothing else, interviewing outside candidates should add ideas on how they can evolve.
Still, whenever the Niners do hire the next defensive coordinator, it's unlikely that the style of defense they play will be vastly different from what it has been for the past seven years.
"We like who we are, what we do as a defense, and I don't think we want to have some wholesale departure from that," Lynch said. "I know we don't."