Column: In NFL free agency, running backs might not hit paydirt

Not only did DeMarco Murray set a Dallas Cowboys record by running for 1,845 yards last season, but he won the NFL’s rushing crown.

That bolsters his resume, but not necessarily the likelihood he’ll stay in Dallas.

When free agency begins Tuesday, Murray could find the waters a bit tepid. Whereas having a strong running game used to be the cornerstone of the vast majority of top-shelf teams — and it certainly helped the Cowboys in 2014 — a lot of franchises are perfectly comfortable cutting corners in that department these days.

There’s also a glut of familiar running backs on track to hit the open market, among them San Francisco’s Frank Gore, Baltimore’s Justin Forsett, San Diego’s Ryan Mathews and Buffalo’s C.J. Spiller.

The Cowboys have invested a lot of money in their offensive line, most recently re-signing right tackle Doug Free, and are prepared to say goodbye to Murray if he’s too costly and roll the dice with a less-expensive back running behind that sturdy wall of blockers.

“The runner isn’t the only one who is part of running the football,” Cowboys Coach Jason Garrett said. “Controlling the line of scrimmage is big. We’ve made a lot of organizational emphasis over the last few years to use our resources to shore up that offensive line. I think that’s paid dividends for us. But the runner does matter.”

The player who figures to set off the biggest bidding war in this free-agency class is Detroit defensive tackle Ndamukong Suh, who could be a headache for his own team with his fines and suspensions but consistently has been a nightmare for opposing blockers.

Among the teams believed to be lining up for Suh’s services are Miami, Oakland, San Diego . . . and of course the Lions.

“Obviously he’s an important part of what we’re doing,” said Martin Mayhew, Detroit’s general manager. “He’s a perennial All-Pro, he’s a Pro Bowl player. It’s difficult to replace his production in the middle of our defense, but obviously it would be a setback not to have him on our football team.”

Green Bay’s Randall Cobb is set to hit the open market and heads an impressive class of free-agent receivers that includes Philadelphia’s Jeremy

Maclin, Baltimore’s Torrey Smith and San Francisco’s Michael Crabtree. The Cowboys placed the franchise tag on star receiver Dez Bryant.

Of course, not everyone who is scheduled to become a free agent is destined to wind up in a new uniform. Many are simply re-signed by their current teams.

The New England Patriots, fresh off their Super Bowl victory, are faced with the daunting task of re-signing cornerbacks Darrelle Revis and Devin McCourty, both hugely instrumental in the club’s championship season.

Saturday morning marked the start of a three-day period during which teams could begin negotiating with players on the verge of becoming free agents. Teams can talk money but are not allowed to make offers during this period.

If Murray were to leave Dallas, the Cowboys wouldn’t be the first team this off-season to bid farewell to a star tailback. The Philadelphia Eagles, for instance, were willing to trade 2013 rushing champion LeSean McCoy to Buffalo for Kiko Alonso, a third-year linebacker who sat out the entire 2014 season with a torn ACL.

Meanwhile, teams such as Tennessee (Chris Johnson), Miami (Knowshon Moreno) and Atlanta (Steven Jackson) have lived through the torment of paying big money to a back, only to watch him underperform. Both the Cleveland Browns and Indianapolis Colts lived through the disappointment of Trent Richardson. And in the 2014 draft, 53 players came off the board before the first running back was taken — Bishop Sankey, by Tennessee — the longest tailback drought to start a draft in league history.

That’s not to say all teams are skittish about prying open their wallets for talented ballcarriers. Seattle just signed Marshawn Lynch to an extension through 2017 that pays him $12 million for the upcoming season. McCoy has a cap number of $10.25 million for 2015. Mark Ingram reportedly has agreed to an extension with New Orleans.

And former NFL most valuable player Adrian Peterson is scheduled to make $12.75 million in Minnesota this fall, although he has expressed reservations about returning to the Vikings. The running back was suspended for the final 15 games last season, pleading no contest to a charge of misdemeanor reckless assault for striking his 4-year-old son with a switch.

Vikings General Manager Rick Spielman called Peterson a “unique football player” when asked about him last month at the scouting combine.

“I’m sure he’s doing everything he can to not only make himself better as a football player but also a better person off the field, and that’s the type of person Adrian is,” Spielman said.

“There’s no question, I don’t think any team in the NFL wouldn’t want an Adrian Peterson-caliber running back on their football team.”

Of course, that means paying big bucks. In today’s pass-happy NFL, not every team is willing to do that.

sam.farmer@latimes.com

Twitter: @LATimesfarmer