Steelers 2015 depth chart: Tackles have become a strength in Pittsburgh

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 -- Offensive tackle was a point of contention for the Steelers two years ago, but 2012 seventh-round pick Kelvin Beachum and 2011 second-rounder Marcus Gilbert have solidified the left and right tackle spots, respectively, the past two seasons.

Beachum isn't a prototypical left tackle, but his attention to detail and steadily improving technique helped him succeed during 33 starts in 38 games played. Beachum played 31 games with 28 starts the past two seasons. Gilbert has started 46 of 47 games in his brief NFL career. He missed two games in 2011, 11 in 2012 and four last season after playing all 16 in 2013. Gilbert's foot injury late in the season did not need surgery, so he should be ready to work out this spring and certainly be ready for training camp.

Beachum is scheduled to make $660,000 this season, an extreme bargain for a starting left tackle, but he is going to be an unrestricted free agent next year. He is the third member of the starting offensive line with a contract expiring after this season. Gilbert has not been spectacular, either, but solid with an upside and room for improvement. He signed a five-year contract extension through 2019 worth nearly $31 million. His cap hit is about $7 million this year.

Mike Adams is the lone backup tackle. He was selected in the second round in 2012 and projected to be the team's starter on the left side, but his play primarily has ranged from adequate to poor, especially as a pass-blocker. His contract also expires after this season, and if his play doesn't improve drastically this year he could be done in Pittsburgh.

Steelers 2015 Depth Chart Review

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

Off-field issues have dogged him since college, but the Steelers drafted Adams anyway and likely have regretted it. His base salary this year is $873,225, a big payday for a seldom-used underachiever, but it could be his final one with the Steelers. Alejandro Villanueva (6-foot-9, 277 pounds) and Mitchell Van Dyk (6-7, 299) have signed future contracts. Both are intriguing prospects.

Villanueva is a former U.S. Army Ranger and special forces operator, but his experience is limited and he will be 27 years old this year. So, while he could become a good player, he doesn't have a lot of time. Van Dyk has been in the league a couple years, but has no game experience.

The Steelers should continue to look at tackles to upgrade the position, but it's unlikely they will take one with a high choice during this year's NFL Draft. It wouldn't be surprising, however, if one was chosen in the middle rounds.