NFL: Biggest questions facing the NFC West in 2017

San Francisco 49ers: Are there pieces in place for the new 4-3 Under defense?

With the hiring of Shanahan as head coach, the new staff has been equipped with coordinators and coaches under familiar schemes across the league. At Defensive Coordinator, the team hired Pete Carroll disciple Robert Saleh, who will incorporate the 4-3 Under defensive scheme, a detailed defensive plan that was made famous in Seattle in recent seasons and also operated by the speedy Atlanta Falcons defense.

So the question in place inquires about the key players to make this scheme successful. The system calls for speed and versatility at the linebacker position, cornerbacks that can be quite useful in Cover 3, and plenty of versatility along the defensive line. The combination of defensive ends Arik Armstead, DeForest Buckner, and 2017 1st rounder Solomon Thomas are skilled enough to make any defense better. But the odds say that all three along with defensive tackles Earl Mitchell and Quinton Dial will need a little reshuffling to get the right players at the right spot.

Drafting Reuben Foster late in the first round this year gives the team their athletic linebacker who can roam and create havoc. Veteran linebacker NaVorro Bowman is expected to make a full recovery following last season’s Achilles injury.  His presence is essential with Foster in a defense that will see plenty of nickel looks with two linebackers on the field.

Much is expected of them in a very young and unproven group of corners, Dontae Johnson and Rashard Robinson, who combined to start six games last season. There are plenty of youth on the 49ers defense, but that youth also provides plenty of questions for a structured scheme.