Allen Park — Detroit Lions general manager Bob Quinn made the offensive line his priority during his first year with the franchise and the unit will merit plenty of attention once again this offseason.

Last year, Quinn utilized the draft to bolster the blocking. He used three of the team’s first five picks on linemen. That netted starters Taylor Decker and Graham Glasgow, plus a future piece in Joe Dahl. This year, the two senior members on the youthful unit are set to be unrestricted free agents.

Riley Reiff, the team’s first-round pick in 2012, and Larry Warford, a third-round choice in 2013, are scheduled to hit the open market. Quinn has to decide whether he wants to invest in continuity or continue to rebuild the line from the ground up.

“Nothing has been decided on either one of those guys,” Quinn said last week. “One thing that we do, we try not to make rash decisions on guys like that that are just coming into their free agent year. Our season just ended four days ago. I think those decisions are in the months and weeks to come.”

Cap space is always fluid, and particularly fickle this time of year, but the Lions currently have more than $40 million to play with entering the offseason. Reiff and Warford won’t come cheap, but if the Lions want to retain them, they can afford to do it.

It’s challenging to assign value to linemen. Even the stats that do exist, such as sacks allowed or penalties committed, don’t tell much of a story. And unless you’re willing to commit hundreds of hours to film study, it’s easier to lean on the assessment of others.

Pro Football Focus, which grades every snap for every player, has generally thought highly of Warford during his career. The publication ranked him as the 22nd guard in the NFL this season, consistent as both a pass protector and run blocker.

That kind of consistency, on the open market, often earns a top-10 contract at your position. That would make the going rate for Warford between $6-7 million per season.

Reiff is trickier. A left tackle converted to the right side, he can make much more on the open market if he can find someone willing to pay him to protect the blindside once again.

An average starting left tackle earns between $9-10 million, where $6-7 million would be a top salary for a right tackle. If another team views Reiff as a left tackle, and are willing to pay him the going rate at that spot, it’s difficult to imagine Quinn competing with the offer.

If Reiff only generates interest as a right tackle, then the decisions are interesting. Quinn and his staff must assess how the team’s line is trending and whether the cost of retaining one or both of the free agents is worth the price tag.

Detroit does have replacement options on the roster, but their ability to step in and perform at a similar level is unknown. At right guard, Dahl and 2015 first-round pick Laken Tomlinson could complete for the job, along with a potential addition via the draft.

Tomlinson played right guard for four years at Duke and many feel a move back to that side would help maximize his potential.

At right tackle, Corey Robinson would be the favorite to replace Reiff. The two-year pro has been durable and reliable for the Lions, but wasn’t viewed as favorably by PFF, which ranked him 48th among tackles last season.

Robinson is a cheap alternative. A seventh-round pick in 2015, he has a cap hit of $630,000 next year. He started two games in place of Reiff last season with mixed results, but 6-foot-7, 317-pounder showcased some intriguing potential throughout training camp and the preseason. He’ll also be coming off a season-ending foot injury he suffered in Week 17.

Other options would be Cornelius Lucas, a restricted free agent, who has seven starts under his belt, or a draft pick.

Quinn didn’t have decisions quite like this last season. The two most important free agents he re-signed were defensive tackle Haloti Ngata and linebacker Tahir Whitehead. Those were a pair of two-year deals with wiggle room to move on after a year if the players weren’t working out. Reiff and Warford will command longer commitments at a steeper price at mission critical positions.

The Lions have a couple months to make the decisions, but Quinn is feeling prepared.

“I’ve had my staff in place here for close to a year now, so we feel like we’re in a much better place in terms of the preparation,” Quinn said. “Now, a lot of the heavy lifting is still to come, but I feel like we’re in a good spot in getting ready for the offseason.” @justin_rogers