A breakdown of the Pittsburgh Steelers' 2018 free-agent signings.

Morgan Burnett, S

The Steelers are expected to sign safety Morgan Burnett, who played the past eight years for the Green Bay Packers. Here’s a closer look at the signing:

Grade: B-plus. The Steelers fill another big need with a versatile safety who can play in the box or in pass coverage. After starting 102 games for Green Bay, Burnett can step in right away and replace Mike Mitchell, who was released last week.

What it means: Burnett was one of the top safeties on the market and the first true free agent from the position to sign, which says three things: First, the Steelers are serious about getting better on the back end; second, they don’t have to reach for a safety in the draft; and third, the safety market was affordable enough for Pittsburgh to capitalize. The Steelers entered the weekend with about $6.5 million in cap space and signed linebacker Jon Bostic to a two-year, $4 million deal Monday. Money is tight, so the Steelers must feel good about this deal.

What’s the risk: Burnett is 29 and hasn’t played a full season since 2012. He’s productive when available, but nagging injuries have been an issue. Although the Steelers value veteran leadership, they’ve looked to get younger and faster in recent years. This move doesn’t follow that path. But the defense needs reliability at this spot, and Burnett should provide that.

Jon Bostic, LB

The Steelers signed Jon Bostic, who played last season for the Indianapolis Colts. Here's a closer look at the signing:

Grade: B. The Steelers stayed away from the expensive linebackers in the $5 million- to $9 million-per year range and opted for a journeyman who capitalized on a starting chance in Indianapolis with 97 tackles and a sack. Bostic, who agreed to a two-year contract, will be viewed as a good stopgap to replace Ryan Shazier until a draft pick develops.

What it means: The Steelers' inside linebacker position opposite Vince Williams is wide open, and Bostic signed with the expectation that he'll compete for a starting job. The team was not planning to re-sign Sean Spence. Tyler Matakevich is primarily Williams' backup, although he can play both spots. Bostic is a former second-round pick who ran a 4.61 in the 40 at the combine. He's on his fourth team since 2015, so this is hardly a long-term option unless Bostic majorly builds off his 2017 campaign.

What’s the risk: Limited risk for a player who will probably command about $2 million per year. The Steelers entered the weekend with about $6.5 million in cap space, just enough to add linebacker depth and maybe special-teams help. This is a smart signing for a team that wasn't going to spend wildly. Shazier isn't playing in 2018, and the team couldn't sit idle after the run defense struggled late in the year, giving up at least 150 yards in three of the final six games.