SANTA CLARA, Calif. -- In some ways, Sunday's meeting between the Seattle Seahawks and San Francisco 49ers will bring things full circle between the two sides from a defensive perspective.
Long before 49ers defensive coordinator Robert Saleh was coaching in the league, let alone learning the ropes from the Seahawks' Pete Carroll in Seattle, Carroll was serving as the 49ers' defensive coordinator under then-coach George Seifert.
Seifert was the architect of a defense that was often overshadowed by one of the league's best offenses. But Seifert's 4-3 scheme was plenty stout in its own right. Headlining that unit more often than not was the player manning the "elephant" defensive end position. It was the spot reserved for the best pass-rusher -- think Charles Haley or Chris Doleman.
In the years since Carroll worked for Seifert, that defense has evolved and one of those changes came in the name of that position. The change came as a direct result of a player who wouldn't be near the top of the list when 49ers fans rattle off successful "elephants."
When Carroll was in San Francisco, the 49ers used a second-round pick on USC defensive end Israel Ifeanyi. As Carroll tells it, Ifeanyi called home to his father in Nigeria after they drafted him.
"We brought him in the day we drafted him and he came in and called his father in Africa and said, 'I have been drafted into the NFL and they want me to play elephant,'" Carroll said. "I never thought that father could ever understand what his kid was telling him right there. 'I play in the NFL and I am now an elephant.' So we, just in time, just adjusted the word."
In the current iteration of Carroll's defense, the position is called the Leo. The comparisons between the schemes of Carroll and Seifert mostly end there. However, the comparisons between the current 49ers' and Seahawks' defenses are almost unlimited. They're essentially the same, which should be no surprise considering the proliferation of Carroll's understudies serving as defensive coordinators or head coaches around the league.
There's former Seahawks coordinator Dan Quinn, now the head coach in Atlanta. Gus Bradley, also a former Seahawks coordinator, is running the Los Angeles Chargers' defense. And there's Saleh, the man selected by 49ers coach Kyle Shanahan to install the same aggressive 4-3 in San Francisco that Saleh had been a part of in Jacksonville and for three years working with Carroll in Seattle.
As offensive coordinator in Atlanta the past two years, Shanahan got to see it up close with Quinn running the show. But it's a defense he has long admired. Shanahan's ties to the scheme date to his time as a young assistant in Tampa Bay, where the Buccaneers ran Monte Kiffin's Tampa 2. Kiffin's zone-based defense featured an attacking front seven and often ranked near the top of the league in most major categories.
While Carroll's defense isn't exactly the same, it has roots from Carroll's time as a graduate assistant under Kiffin at Arkansas in 1977. After accumulating knowledge of various defensive schemes around the league in his nine years as an offensive coordinator, Shanahan came to believe that Carroll's evolution of that Tampa 2 system was what he wanted when he took over a program.
“It's a very sound scheme that starts with stopping the run," Shanahan said. "Anytime your base defense is an eight-man front, it's very gap-oriented. It's tough to run the ball against. You're always outnumbered on offense unless you use the quarterback. So your numbers are never there. Usually that gives you the best chance to stop the run. It forces you to throw. And when you have a sound scheme versus the run, but it's very good in coverage, that eliminates big plays with their zone drops, they make you work all the way down the field.
"So it's extremely tough to get explosives on. It's tough to go against. They make you work for everything and it's something that you don't have to reinvent the wheel every week. It's something that if you just do over and over and over again, it's hard not to get better at it."
Indeed, the beauty of Carroll's system is found in its simplicity. At the base is an eight-man front, which allows all of those defenders to attack rather than wait and react. Coverage-wise, it's all about the Cover 3 zone and various offshoots of it. That defense asks both corners to play zone with a safety roving over the top. The first priority is to take away the run with the other safety playing near the line of scrimmage.
Since Carroll arrived in Seattle in 2010, the Seahawks are first in the NFL in fewest yards allowed (308.8), yards allowed per play (4.95), passing yards allowed (210.1) and points allowed per game (18.04). Seattle is also tied for fifth in interceptions (119) and tied for sixth in takeaways (190).
The goal in San Francisco is to eventually be a group capable of putting up similar numbers. Carroll believes Saleh has the tools necessary to succeed.
"[I'm] not surprised at all that he has arrived here as a coordinator in the league," Carroll said. "Great worker, brilliant guy, good communicator, gets it, great demeanor about him, a lot of energy and I'm not surprised at all."
In the first week under first-time coordinator Saleh, the Niners' defense held its own against Carolina, limiting the Panthers to 287 total yards. But it didn't generate much pass-rush. For his part, Saleh often reminds that he's not just outright copying Carroll's defense so much as using the basics as a foundation and adding wrinkles of his own.
Still, the 49ers spent plenty of time in the offseason studying the defenses in Seattle, Jacksonville and Atlanta. One thing Saleh asks his players to seek when watching the film is potential weaknesses in the scheme. Those conversations lead to some of those aforementioned wrinkles and adjustments that might be needed on the fly.
"I'm excited for this group because they really believe in the things they're capable of and they really believe in the system," Saleh said. "It's cool to see other teams like Jacksonville, Atlanta, Seattle and now the Chargers to have success, and them understand they can do that too. There's a lot of tape for them to watch to show that what we're asking, they're capable of. Especially this group. From a maturation standpoint, they're so young. I do believe that it's in this group."
Expecting the Niners to turn into a dominant defense right away is unrealistic. Part of what has allowed Seattle to have such success is a combination of continuity and supreme talent in cornerback Richard Sherman, safeties Earl Thomas and Kam Chancellor, linebacker Bobby Wagner, and a defensive line loaded across the board.
The 49ers have none of those things, though there are potential building blocks in place.
"They have been building something special over there and they've been building that defense for so long, you start to understand how you get attacked and what your weak spots are," said 49ers linebacker Brock Coyle, who spent the past three years in Seattle. "I think that's the difference for them is just that they've had that defense for so long. They just know."