After T.J. Lang and Rick Wagner, can Lions invest heavily again on O-line?

With free agency approaching (March 14), we're analyzing the offensive line of the Detroit Lions.

2018 cap hits of top returnees:

RG T.J. Lang: $10,869,791

RT Rick Wagner: $5.9 million

LT Taylor Decker: $2,990,994

OG/C Graham Glasgow: $809,855

OT Corey Robinson: $719,477

Pending free agents: Travis Swanson, Greg Robinson, Don Barclay, Zac Kerin (restricted)

Key stat: The Lions were last in the league in yards per rush and rushing yards per game last season. Matthew Stafford was also sacked 47 times -- second-worst among NFL quarterbacks (Indianapolis' Jacoby Brissett was sacked 52 times).

Money matters: This was general manager Bob Quinn's big focus last free agency period, bringing in Lang from Green Bay and Wagner from Baltimore. Both were good when healthy, but missed three games each last season. Decker remains a bargain at left tackle under his rookie contract, as does Glasgow. But Detroit has a good amount of money tied up in the right side of its line. The question is whether the Lions will add another high-priced free agent to the interior of the line or try to fix that problem internally or in the draft.

Big picture: It's tough to know how well Quinn's big picture is playing out here, because of last year's starting five, only Glasgow played every game. Besides Lang and Wagner, Decker missed eight games and Swanson five. Detroit ended up mixing-and-matching most of the season, leading to instability and a lack of success.

The four returning starters are locked up through 2019, so Detroit has the chance to build chemistry -- especially if Joe Dahl (also under contract until 2019) were to win the fifth starting job, because he's been around the organization. The tackle position seems set with Decker, Wagner, Corey Robinson, Emmett Cleary and Brian Mihalik all under contract. It's possible the Lions add a player with tackle flexibility as a reserve, but the main focus should be the interior.

After the firing of line coach Ron Prince, a scheme change can be expected up front. Getting enough blocking to have a semblance of a run game and protecting the franchise quarterback are the focal points, so money could be worth spending here if the Lions feel this is the best way to go.

At this point it would be surprising to see any of the Lions' free agents -- including Swanson -- return next season, but things can change.

The game plan: The top available option at guard, Andrew Norwell, would appear way too expensive for Detroit to get involved with as he's expected to net more than Lang did last year. There are, though, other options.

Josh Sitton, who has played with Green Bay and Chicago and has a familiarity with Lang, is an option if he's willing to come in at a reasonable price. Justin Pugh is another guard who could fit in that similar price range.

If the Lions don't want to go very expensive on the line and want to get a guy who can compete for a starting job, Jeremiah Sirles could be a guy to watch at guard. He was coached by new line coach Jeff Davidson when Davidson was in Minnesota and Sirles can play multiple positions. Matt Slauson is older, but also has experience under Davidson.

If Detroit decided to keep Glasgow at guard, Ryan Jensen is the top option at center (and would have familiarity with Wagner from their Baltimore days). Weston Richburg (Giants) would be a potentially cheaper option. If the Lions are looking for an older center possibility with connections to Davidson, John Sullivan would be a guy to consider. He played five seasons under Davidson in Minnesota and has been mostly reliable throughout his career, missing six games total since the 2008 season.

If Detroit decides to look to the draft, UTEP's Will Hernandez could be an option in the first round at No. 20 and Auburn's Braden Smith and Virginia Tech’s Wyatt Teller could be options on Day 2. The question mark is Ohio State's Billy Price, who suffered a pectoral injury at the combine. If he slips in the draft, the Lions should run to take him on Day 2. He could even be a consideration on the first day. But this could all be dictated -- like last year -- by Detroit's decisions during free agency.