There are three two key positions that every team needs if it wants to excel on defense: pass rushers and cornerbacks. After adding Nick Bosa and Dee Ford to DeForest Buckner and Arik Armstead, it looked like the 49ers probably had the former position sown up.
Cornerback was somewhat less certain. Richard Sherman was not back to his best last season, though he was more than solid. On the other side, Ahkello Witherspoon was inconsistent and clearly frustrated his coaches with his attitude. Despite that, he demonstrated the talent on several plays to suggest he could yet become a high calibre NFL cornerback.