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Marcio Jose Sanchez/Associated Press

Defensive Coordinator: Robert Saleh

Base Defense: 4-3

After the failed Chip Kelly experiment in 2016, the 49ers have a brand new front office and coaching staff heading into 2017. New defensive coordinator Robert Saleh will transition the team from a big 3-4 team under Kelly to a faster 4-3 defense. The goal is to allow their linebackers to fly to the football instead of taking on blocks. However, this means that the two former first-round picks in Arik Armstead and DeForest Buckner won't be playing the position they were drafted to play; 3-4 defensive end.

That isn't necessarily a bad thing, as the team was dreadful with the two as its ends. It's not their fault alone, but the rest of the roster just wasn't good enough around them to stay in the 3-4. They just weren't dominant enough to keep running that scheme.

In 2016, the 49ers gave up the most yards and points in the league. They allowed more than 165 rushing yards per game as teams gashed them on the ground each and every week. They were easily the worst defense in the league, which seems crazy considering how dominant of a unit they were just a few years ago under Jim Harbaugh.

In the first round, the 49ers used their first two selections on talented defenders in Solomon Thomas and linebacker Reuben Foster to help get back the speed on defense. While both players will excel in the NFL, it's unlikely they will drastically change this defense throughout the 2017 season.

San Francisco still needs to add true 4-3 defensive ends who can get after the quarterback, but they should be better against the run this year with improved linebacker play. However, this is still one of the worst defenses in the NFL.