The knowledge from Doug Free.

FRISCO, Texas — Over and over the past few seasons, the Dallas Cowboys’ offensive linemen kept hinting at Doug Free’s importance. They didn’t want to delay expressing their gratitude to the veteran right tackle.

Free opted to retire in the offseason, calling it a career after 10 seasons. Perhaps fitting to his low-key career, he had a retirement party away from the bright lights of a Dallas steakhouse for a seafood restaurant not far from his suburban home.

All of his offensive line teammates showed up. So did Jason Witten. So did Tony Romo.

If they didn’t want to delay their gratitude when he played, they certainly didn’t want to delay it when Free opted to walk away.

We’re going over drills that we’ve done a lot, but really kind of moving back to the basics, trying to get everybody back on the same page where before there was a little more veteran guys who’d been around and you had one or two guys that kind of had to figure it out. Now it’s the majority of the guys that are just seeing their first offseason with this.

There is no secret sauce to the formula that has made the Cowboys’ offensive line either the best or among the best the last few seasons. Talent helps. Smith, Frederick and Martin were first-round picks. Last year they were named first-team All-Pros. The running back, Ezekiel Elliott, matters, as Jason Garrett likes to say. The scheme helps too.

But the work matters most. Free made sure the group was about work more than words. They pride themselves on being the hardest-working group on the team and the coaches believe that trickles down to everybody else.