On March 11, 2015, the Cardinals signed free-agent center A.Q. Shipley. On March 12, they released veteran center Lyle Sendlein.

As the Cardinals work with their center situation in 2020, it's a note to file away, just in case.

Shipley, who has been the Cards' starting center since 2016 -- save for 2018, when he tore his ACL in training camp -- is a free agent. The Cardinals head into the offseason with third-year pro Mason Cole slated to start at the position. Cole started every game at center as a rookie when Shipley was hurt, but did not beat Shipley out last offseason. Cole instead was the Cards' top reserve offensive lineman, starting at guard when injuries occurred and not coincidentally getting some game reps at center with the future in mind.

"Mason Cole started every game at center two years ago," GM Steve Keim said about the Cards' view of the position right now. "Extremely smart, he's tough, really, really athletic at climbing and getting to the second level. He's a great fit for our offensive scheme."

The Cards also have second-year pro Lamont Gaillard, who is the early favorite to take Cole's place as the top offensive line backup. This was always the path the Cards have wanted for Cole, who was a third-round pick in 2018. Shipley, meanwhile, turns 34 next month.

But there is the other side to 2015 for the Cardinals and Keim. In training camp, on Aug. 7 with a week before preseason games started, Sendlein was re-signed. Shipley had been the starting center but the Cards decided they needed more at the spot. Backup Ted Larsen had struggled. Sendlein ended up starting all season for a team that reached the NFC Championship game.

Keim was asked Wednesday if the Cardinals had moved on from Shipley or if he could return.

"I wouldn't rule anything out, is what I would say," Keim said.