The 49ers’ defense looks head and shoulders better than the 2018 unit through the first four games of the season. The biggest difference from last year to this year is their ability to generate turnovers. After just seven takeaways in 2018, the 49ers have 11 already this season.
San Francisco has been able to ride its defense to the team’s first 4-0 start since the 1990 season.
We went back through the first four games and gave each position group a quarterly grade:
Defensive line
Improving the pass rush was a point of emphasis in the offseason for the 49ers, and their changes worked. The defensive line is what’s driving the defense’s success. Nick Bosa and DeForest Buckner have led the way with 3.0 sacks each with Dee Ford and Arik Armstead each with 2.0. Not only has the line been able to create a pass rush, but the they’ve also held opposing teams to 81.75 rushing yards per game, good for fifth-best in the league, and they have given up a rushing touchdown.
Grade: A
Linebacker
Kwon Alexander might have been the biggest acquisition in the offseason outside of the additions on the defensive line. Alexander has added a level of intensity to the defense that was apparent the first three weeks. He recorded three tackles in the first quarter against Tampa Bay before being ejected, but then followed up with six and seven tackles the following two weeks. Fred Warner continues to rack up tackles with 25 on the season to follow a rookie year where he finished with 124. Dre Greenlaw earned a starting job as the Sam linebacker entering the season, but with the team generally playing in sub packages, he hasn’t seen more than 20 snaps in a game since Week 1.
Grade: B
Secondary
What a difference a new pass rush makes for. The 49ers didn’t make many changes to their personnel in the back end with the hope that improving the pass rush would elevate the play of the defensive backs. It’s working. Five of the team’s seven interceptions have come from the secondary, with Richard Sherman and K’waun Williams pulling down two apiece. Ahkello Witherspoon was playing the best he’s played in his three-year career before a foot injury sidelined him in Week 3. Emmanuel Moseley allowed one catch on three targets while starting for Witherspoon in Week 5. The secondary has allowed just 175.8 passing yards per game, the second lowest total in the NFL.
Grade: A
