2015 Steelers depth chart: Lots of unknowns at outside linebacker

The Pittsburgh Steelers hit free agency hard last year, bringing in a handful of veteran players to earn starting roles and improve depth.

Here is a position-by-position look at the Steelers depth chart going into this year's March 10 start of free agency.

PITTSBURGH -- With three unrestricted free agents among their top outside linebackers from last season -- James Harrison, Arthur Moats and Jason Worilds -- the Steelers have a lot of work to do to shore up the position this year.

A lot hinges on what happens with Worilds. While Moats likely will be re-signed at minimal cost and Harrison not brought back, Worilds' status is in question. He played last year under the transition tag at $9.754 million and did not make enough plays to justify that. However, the Steelers need to re-sign Worilds if at all possible just because they have no other proven outside backers on the roster, even though he thinks a lot more highly of himself.

That might be his downfall with the Steelers, who aren't likely to overpay for Worilds, although he was their top pass-rusher last season with 7.5 sacks and 18 quarterback pressures. He also was asked to drop into pass coverage, but that wasn't his strong suit. And he missed only about a dozen or so snaps all year, so he was durable. Worilds needs to do more, though, such as record twice as many sacks and in general make more plays. It remains to be seen if the Steelers can reach a long-term contract agreement with him.

Steelers 2015 Depth Chart Review

Reviewing where the Steelers stand in terms of depth heading into free agency and the draft.

Harrison saved the Steelers defense last year by signing with them just a few weeks after announcing his retirement. At 37, it's unlikely that he could repeat his modest numbers from last season, although there were several games where Harrison looked like he was the havoc-producing playmaker of old. He had 5.5 sacks, all in three games, and 14 quarterback pressures. While those numbers are solid in 11 games, he wore down at the end of the year, and there's no indication that he wouldn't do it again after a grueling camp and preseason, which he missed all of last year. If they could get a guarantee that Harrison will continue to play at that high level this year and not get injured, the Steelers might take another shot to sign him. But there are no guarantees. Harrison reportedly is working out to prepare to play this season.

Jarvis Jones, the Steelers' No. 1 pick in 2013, has two years remaining on his rookie contract with a team option for a fifth total season. He is far from earning that fifth year. Jones was slated to be a starter since he was drafted and hasn't embraced that role. He has shown some flashes of brilliance, but they have been brief. He missed the majority of last season due to an injury and played just 16 snaps combined over the final three games.

Jones is in a group of young players who has to take his game to the next level this year for the Steelers to be successful. By all accounts, Jones was coming around when he was injured Sept. 21, but that's basically two wasted seasons for him. That has to end this year.

Moats was a capable backup and occasional starter last year, and he should return to that role if the Steelers can re-sign him this year. They likely will try to get him at a bargain, even though he eventually was beaten out by Harrison at midseason. Still, Moats tallied four sacks and seven quarterback pressures, two forced fumbles and one fumble recovery. His solid play and team spirit would be an excellent addition this year as well.

The other outside linebackers on the Steelers spring roster include 2014 sixth-round pick Jordan Zumwalt, preseason surprise Howard Jones -- who spent last year on the practice squad -- and veteran Shawn Lemon. Zumwalt was on injured reserve all year after a serious groin injury during training camp and the preseason, so he couldn't practice with the team. He also was prohibited from practicing during OTAs due to the ridiculous rule that players can't join their NFL teams until their college class graduates. So, it was a wasted season, but he has a huge upside and needs to perform at a high level this year.

Howard Jones was an undrafted rookie defensive end from Shepherd University in Shepherdstown, W.Va., but he made the Steelers with his big-play capabilities as an outside linebacker and special teams. After what basically amounts to a redshirt season, Jones could be a capable backup this year.

The 6-foot-1, 235-pound Lemon is an intriguing prospect who will turn 27 a couple weeks before this season begins. He played collegiately at Akron until 2011 and went to the Canadian Football League. Lemon moved on to the Arena Football League and then returned to the CFL in 2012 and played for Edmonton and Calgary until last season. The Stampeders won the Grey Cup last year with Lemon's 13 sacks, eight forced fumbles and an interception in 18 starts.