Editor's Note: Here is the fourth installment of a five-part series on the 49ers' top offseason priorities.

The Carolina Panthers ranked as the second-best offensive line in the NFL last season, according to Pro Football Focus.

But the Denver Broncos’ pass rush made that unit look pedestrian, just as it did against Pittsburgh and New England en route to the Super Bowl.

[REWIND: Top 5 free agent targets to improve 49ers' pass rush]

The lesson here is that a great pass rush — virtually acting alone — not only can win a Super Bowl, it did win a Super Bowl.

And that brings us to the current state of the 49ers.

The 49ers ranked 29th in the NFL with just 28 sacks last season and there appears to be very little potential for a dramatic improvement with the pass-rushers already in place.

Aaron Lynch is a solid starter. He was the team’s best pass-rusher for most of the season with 6.5 sacks in the first 10 games. But he was shut out the remainder of the season while missing 2 1/2 games due to a concussion.

Ahmad Brooks, who turns 32 next month, tied with Lynch for the team-lead in sacks. If the 49ers are looking to move on from Brooks, there is one major problem: The team does not appear to have his replacement on the roster.

Tank Carradine has been a major disappointment since the 49ers selected him in the second round of the 2013 draft. In 23 games, Carradine has three sacks. The 49ers’ coaching staff decided late in the season to work Carradine as an outside pass rusher in nickel situations. That role appears to be his best hope to make a contribution as he enters the final year of his original four-year contract.

 

[RELATED: 49ers have new role for Carradine to inject life into pass rush]

Corey Lemonier, a third-round pick in 2013, has one sack in 42 career games. He was inactive for six games last season. Eli Harold, a third-round pick last year, was held without a sack while appearing in all 16 games as a rookie.

The 49ers have money to spend, but the top free-agent pass rushers — Von Miller (Denver), Muhammad Wilkerson (N.Y. Jets) and Olivier Vernon (Miami) — are likely to be franchised by their current teams. Still, the 49ers can be expected to sign a player who can step into the rotation. The 49ers need more depth when it comes to putting heat on the quarterback with the increased number of snaps that unit can be expected to play in Chip Kelly's first season as head coach.

Of course, the 49ers will also look to add via the draft. DeForest Buckner (Oregon), Shaq Lawson (Clemson) and Noah Spence (Eastern Kentucky) are among the candidates the 49ers could consider at No. 7 overall if the team is looking to use that pick on a pure pass-rusher.