With free agency approaching (March 14), we're analyzing the defensive backs with the Detroit Lions.

2018 cap hits of top returnees:

S Glover Quin: $6,516,666

CB Darius Slay: $6,126,269

CB/S Quandre Diggs: $1,933,838

CB Teez Tabor: $1,096,131

S Miles Killebrew: $774,641

CB Jamal Agnew: $619,594

Pending free agents: CB: Nevin Lawson, D.J. Hayden. S: Tavon Wilson, Don Carey.

Key stat: Slay, Quin and Diggs -- three probable starters in 2018 -- had 14 combined interceptions last season, led by eight from the Pro Bowler Slay.

Money matters: Detroit is locked into its top corner (Slay) and safety (Quin) for the foreseeable future. Both have come at a reasonable price considering their talents, too. Otherwise, it’s a group that doesn’t have a lot of money tied into it. Diggs is in the final year of his contract and is an interesting player because he took so well to his move to safety in the middle of last season. If he continues there -- and continues playing well -- he could be in line for a bigger extension number.

Big picture: This is a position of depth and strength for Detroit at this point in the year. The Lions have stars at both positions and an emerging player in Diggs. Both Tabor and Agnew took steps forward toward the end of their rookie years -- Tabor both on the outside and in the slot and Agnew in the slot.

If Detroit can turn Agnew into a good slot corner along with his All-Pro level at returner, he becomes an incredibly valuable piece. Detroit has good depth here, too, with Miles Killebrew and Charles Washington at safety. That said, the Lions could use some help.

The game plan: This would seem like a free agency play at cornerback and either a free agency or mid-to-late draft play at safety. Wilson, a free agent, played for new coach Matt Patricia in New England and found a strong role with the Lions at strong safety. He was having a good year before his injury opened the opportunity for Diggs. If he comes back, the Lions have a good group of four/five at safety, but he might have played well enough for another team to throw him some good money.

Likewise, it wouldn’t be surprising to see Detroit bring back either Hayden or Lawson (but likely not both) to compete with Tabor for the starting corner spot. Both Hayden and Lawson also have nickel/dime flexibility, which could increase their value to the Lions. Remember, before Lawson won the outside job, he was initially expected to become a nickel. Hayden, meanwhile, had a year with new Lions defensive backs coach Brian Stewart at the University of Houston.

As far as free agents, Malcolm Butler and Trumaine Johnson are the big names at corner but likely would be too expensive for Detroit. Butler’s connection to Patricia, though, makes it interesting, and if the Lions signed either player, that secondary could be considered among the best in the NFL.

As far as cheaper options, Johnson Bademosi -- who was traded from Detroit to New England last year -- is a free agent and could theoretically return. He would be an immediate special teams contributor and resume his role as a depth corner. Sterling Moore is another mid-range type of player with experience and ties to Patricia (he was with the Patriots in 2011 and 2012). Both of these players would be considered more for depth options.

If the Lions want to find a starter -- or a player to compete with Tabor and Agnew -- Philadelphia’s Patrick Robinson could be an option along with the Rams’ Nickell Robey-Coleman, Pittsburgh’s Ross Cockrell and Arizona’s Justin Bethel.

Safety, for now, is not a big need for Detroit, but if Wilson departs, a special-teams-first player like New England’s Nate Ebner or a reunion with former Lion Rafael Bush could make sense. In the draft, a player like Virginia Tech’s Terrell Edmunds, San Diego State’s Kameron Kelly or Penn State’s Marcus Allen could be depth pieces that the Lions could develop into a starter for whenever Quin retires or if Diggs moves on after 2018.