49ers Should Switch to a 4-3 Defense under Coordinator Robert Saleh

The San Francisco 49ers are bringing in Robert Saleh as defensive coordinator. Given Saleh’s background and the team’s current personnel, the Niners should switch from a 3-4 base defense to a 4-3 in 2017.

Former Jacksonville Jaguars linebackers coach Robert Saleh will be joining the San Francisco 49ers ranks as defensive coordinator, per a report from Monday.

Saleh, who also was an assistant on the Seattle Seahawks’ Super Bowl-winning defense in 2013, has familiarity with a 4-3 defense.

And San Francisco’s own defense should follow the lead and switch from its current 3-4 alignment.

San Francisco 49ers

The 49ers have operated in a 3-4 defense ever since 2007, when Greg Manusky was defensive coordinator and the team brought in former linebacker Patrick Willis.

But one of the main reasons San Francisco’s 3-4 scheme worked was due to former Niners defensive end Justin Smith, as Ryan Sakamoto of NinerFans.com pointed out last December.

Smith is now retired, of course, and the 49ers defense has struggled to find the same kind of pocket-wrecking force to deliver similar production.

True, San Francisco’s defense lacks ideal personnel for either scheme. Yet Saleh’s familiarity with a 4-3, added to what the Niners currently have, certainly suggest a switch is pending.

Comparing the 3-4 to a 4-3

Bleacher Report’s Ty Schalter does an excellent job breaking down the differences between a 3-4 and 4-3 scheme.

In a nutshell, for those of you not totally familiar with the layout, a 4-3 defense puts four defensive linemen up front along the line of scrimmage. Instead of four linebackers — two on the outside and two in the inside — in a 3-4 lineup, the 4-3 has just one middle linebacker with two on either flank.

Here’s the base front seven alignment:

Without getting too complicated — go read Schalter’s piece on gap exploitation — a major advantage of a 3-4 scheme is always having someone on a blitz. Yet this comes at the expense of having one less D-lineman up front.

If there is a D-lineman capable of locking up two or three blockers, as was the case with Smith, a 3-4 can work well.

A 4-3 assigns a gap to each lineman, lessening the responsibility and taking the pass-rush responsibility away from the linebackers, to a point, and giving it to the right defensive end.

There are varying techniques to consider, such as the “over” and “under,” but hopefully you get the scoop.

Making the 49ers Personnel Fit

Unfortunately, there isn’t exactly a perfect fit here.

Let’s start with the two cornerstone 49ers defensive linemen, Arik Armstead and DeForest Buckner.

Both are more traditional 3-4 defensive ends and are a bit oversized to play as a 4-3 end. But Buckner could slide inside, freeing up now-linebacker Aaron Lynch to look like a more prototypical 4-3 DE.

Defensive tackle Quinton Dial, who is too undersized to be a prototypical 3-4 nose tackle, should also benefit from a scheme switch. And San Francisco doesn’t have a starting-caliber nose tackle on its roster for the upcoming year.

As for the linebackers, NaVorro Bowman would be able to occupy the middle. No surprises there. Figuring out the WILL (weak-side linebacker) and the SAM (strong-side linebacker) gets a little more intriguing.

Linebacker Ray-Ray Armstrong, who signed a contract extension last year, might be a fit for the WILL. WILL linebackers tend to be more of the coverage types, and Armstrong doubling as a safety makes this a better fit.

SAM linebackers usually have to take on lead blockers in the running game, assuming it’s frequently in their direction. Unfortunately, it’s hard to assume the Niners have one in aging veteran Ahmad Brooks.

NFL Draft and Free Agency

Saleh’s defense has yet to be determined, so it’s still possible the Niners stick in a 3-4. But they lack a true nose tackle for this scheme and could use upgrades at both inside and outside linebacker.

If a 4-3 is desired, neither Armstead nor Buckner are ideal fits. But they aren’t impossible to mold either. And the move would alleviate San Francisco’s need for a dominant middle linebacker to pair with Bowman.

More from Niner Noise

• 49ers 2023 NFL Draft tracker: Pick-by-pick news and analysis
• Predicting 49ers NFL Draft picks by looking at final mocks
• DraftKings NFL Draft Promo – Win $150 Guaranteed on Any $5 Bet 
• 2023 NFL Draft: EDGE Byron Young could be impact player for 49ers
• 5 low-key NFL Draft options for 49ers who are flying under the radar

Regardless, Saleh’s plans will change how the Niners go about free agency and the NFL Draft. And the team’s current defensive makeup isn’t exactly geared toward one way or another in a perfect setting.

Still, making this switch should put San Francisco’s incumbent personnel group into a better position for the upcoming season and, potentially, limit the glaring needs to make notable additions in the draft and free agency as well.

Next: The 49ers All-Decade Team from 2010 through 2016

As such, general manager John Lynch would be able to shore up other pressing areas of concern — another top priority for the red and gold.