Greenlaw will be back to full strength in 2024, but it will be too much of an ask for him to be his complete self on the field probably before the midseason point.

The 49ers need to fill out their depth behind Fred Warner so that those players can come close to matching Greenlaw’s impact in the middle layer of defense.

De’Vondre Campbell has the biggest opportunity in front of him. He will be the favorite to be Warner’s top running mate in September.

Campbell is coming off three solid seasons with the Green Bay Packers. San Francisco would love to have him return to the 100-tackle form of 2021, but even if he produces at the 75-to-100-tackle rate, like he did the last two years, he will be a great addition to the defense.

If Campbell steps up, the 49ers should fill the gaps behind him, Warner and Greenlaw, but if he fails to make an impact, they could be in a tough spot.