A look at the 49ers formation and philosophies after two preseason games

The San Francisco 49ers’ defense has looked fairly impressive in the first two weeks of preseason, which is a significant positive given how early we are in their development curve. It is quite clear that the relative simplicity of the scheme has ensured that the players have been able to adapt quickly, a welcome change after the widely touted issues with last year’s defensive scheme. The team has looked effective against the pass (save a few chunk plays - more on them later) and most importantly has looked much better against the run.

Unsurprisingly of course, there have been some obvious negatives as well and it will be interesting to see whether these negatives are improved on or are increasingly emphasized as we move forward this season.

Regardless, there can be little doubt that Robert Saleh and his assistants have the defense moving in the right direction at this stage. I’ll be breaking down each of the position units, but first, let’s start with some general notes and observations.

• The 49ers have tended to operate in a 4-3 under defense when in base, but we have also occasionally seen them line up in a 4-3 over defense or a base 4-3. The 4-3 over defense has often appeared when facing an offensive formation with a fullback or when the offense lines up two tight ends to the same side of the formation
• The 49ers have used a variety of personnel groupings when they go to nickel packages. When in the regular 4-2-5 nickel defense (4 d-linemen, 2 linebackers and 5 defensive backs) the base down defensive line tends to remain unchanged. The 49ers have also used a 3-3-5 nickel defense, and on those occasions Arik Armstead tends to shift to the strong side and the linebacker on the defensive line plays on the weak side. This grouping will be interesting to follow as the season goes on - as Solomon Thomas and Armstead may rotate at the strong side edge position. The 49ers also have a wide 9 nickel defense, with two 3-tech tackles and two edge rushers. Expect Solomon Thomas, DeForest Buckner and Arik Armstead to rotate as the interior rushers, whilst the edge rushers have consisted of the LEO players or the SAM linebackers.
• The 49ers have lived in a cover 3 defense, infrequently playing cover 1 or either cover 2 man or cover 2 zone. Cover 2 zone has appeared more as a third down defense. The lack of man defense perhaps hints at a lack of faith in the man to man coverage abilities of the 49ers’ defenders and we will have to see how that develops in season. Teams running this defense have shown an increasing shift toward man coverage in recent seasons.
• Saleh has dialed up a variety of blitzes, notably on third downs. He has used his defensive backs and linebackers to generate pressure, sometimes in front of a zone defense and others in front of a man defense with only the single high safety staying deep to protect against the deep pass. His willingness to blitz is undoubtedly exciting and has led to some splash plays - most notably Jaquiski Tartt’s WWE-esque takedown of Paxton Lynch. But does it point to a lack of faith in the 49ers’ 4 man rush? Certainly so far, we have generally seen a lack of pressure against quality competition.