How will the 49ers utilize Nick Bosa and Dee Ford on defense in 2019?

49ers Defensive Line in Base Defense

On plays where the San Francisco 49ers must be prepared for either a run or a pass, they will utilize either 4-3 defensive personnel — four linemen, three linebackers, and four defensive backs — or nickel defensive personnel — four linemen, two linebackers and five defensive backs:

4-3 Defensive Line Personnel

In most situations, including the traditional “base” defense, Bosa will primarily play in the 49ers’ LEO role. Armstead and Thomas are likely to split time at “big end” on the opposite side of the line, which leaves no room for Ford in the front four. However, Ford will still see action in the 4-3, both as a rotational LEO, and potentially on the opposite side of the line as a SAM or OTTO linebacker. While it’s not his strong suit, Ford dropped into coverage on 107 snaps in 2018, per Pro Football Focus:

LEO: Nick Bosa, Dee Ford
DT: DeForest Buckner, Solomon Thomas, Arik Armstead
NT/DT: D.J. Jones, DeForest Buckner
DE: Arik Armstead, Solomon Thomas, Nick Bosa
SAM/OTTO: Mark Nzeocha/Malcolm Smith, Dee Ford

Nickel Defensive Line Personnel

When in nickel personnel, the 49ers substitute a cornerback for their third linebacker, so if Bosa and Ford are on the field, they will need to find a spot in the team’s front four. Depending on the down-and-distance, the two edge rushers could man the team’s two defensive end positions, particularly if San Francisco moves Armstead or Thomas to the inside to either supplement or complement Buckner. Given Ford’s lack of size, opposing offenses will try to attack him in the run game, so 49ers defensive coordinator Robert Saleh will need to provide the undersized defender with proper protection and support in run defense.

LEO: Nick Bosa, Dee Ford
DT: DeForest Buckner, Solomon Thomas, Arik Armstead
NT/DT: D.J. Jones, DeForest Buckner
DE: Arik Armstead, Solomon Thomas, Nick Bosa