Lions general manager  Martin Mayhew is fond of saying free agency and the NFL Draft “aren't the finish line” when it comes to building an NFL roster.

Mayhew backed up his claim Thursday when Detroit claimed former Cowboys G/C Bill Nagy off waivers and placed CB Drew Coleman (concussion) on injured reserve.

At first glance, the move may seem somewhat odd.

Nagy was cut by the Cowboys after he suffered a high-ankle sprain on the same left ankle that he fractured during the 2011 season. Cowboys' offensive line coach Bill Callahan told the Dallas Morning News Wednesday that Nagy underwent surgery on the ankle.

Some Lions fans may question the logic behind claiming a player who has sustained two ankle injuries in the past year, but the move is a solid piece of business for two reasons.

First, the claim is a win-win proposition for Detroit. If Nagy is healthy following his procedure, the Lions gain an O-lineman who was good enough as a rookie to start the first four games of the 2011 season. That Cowboys O-line allowed four sacks in Week 1, but rebounded to allow just one in each of the next three games. As Nagy found his blocking form in Weeks 3 and 4, the Cowboys' rushing game averaged 4.5 yards per carry. If he's unable to compete, he can be placed on IR, and the Lions will keep his contract rights.

Second, the Lions have some familiarity with Dr. Robert Anderson, who -- according to ESPN -- performed Nagy's surgery. Anderson operated on DT Nick Fairley last season, and he also met with T Jason Fox.

That interaction gives Lions trainers the knowledge of Anderson's work they need to evaluate with Nagy's recovery prospects and a possible timetable for his return.

The Nagy pickup is the latest in a series of waiver wire moves over the last three seasons that illustrate Mayhew's skill at combing transaction lists for hidden talent.

He claimed KR/RB Stefan Logan after roster deadline day in 2010. Logan is now a poised to make the team for a third season. Mayhew also pulled the trigger on a claim for RB Keiland Williams, who was released by the Redskins last year following an acrimonious split over the team's decision to move him to FB. Grateful for another chance to compete for RB reps, Williams is having an excellent camp and is providing key help for an injury-depleted rushing unit.

Waiver wire moves often aren't flashy, and they don't usually involve top-flight talent, but Mayhew's recent success at using the system to add talent without trading away resources has served Detroit well. Waiver claims usually arrive with manageable salaries as well, something Mayhew uses to help negotiate Detroit's difficult salary cap issues.

In Nagy, Mayhew seems to have found another player who could help the team without any long-term cost. If the second-year player provides any meaningful contribution, he could be one another diamond in the rough waiver world.

Follow Lions' reporter John Kreger on Twitter at @CBSSportsNFLDET and @JohnKreger.