The focus on the San Francisco 49ers defense heading into 2018 is on the pass rush and the cornerbacks. The team did not make significant changes to the pass rush, while the secondary continued its overhaul of young talent and the addition of Richard Sherman.
A year ago, the 49ers defense ranked No. 28 in pass defense DVOA. Football Outsiders ranked them No. 27 against No. 1 wide receivers, No. 16 against No. 2 wide receivers, dead last against any other wide receivers, and No. 24 covering running backs in the passing game.