Detroit — There are many areas on the Red Wings that need improving.

But one spot that needs special attention is the defense.

It’s a unit that began the season well but gradually, as the long regular season extended into the playoffs, it became a trouble spot.

Too many coverage mistakes, mental mistakes that proved costly, and the lack of a physical edge are all deficiencies that became apparent.

At his season-ending news conference, coach Jeff Blashill admitted the defense has to play better next season.

“What I would say is throughout we have to be a little bit better but our D (defense) corps has to play better,” Blashill said. “Is that a fix from outside? Is that a fix from within? We’ll certainly look at both of those.

“Is there a fix from outside? I don’t know. What I do know is as a group we can be better and that’s including in the D corps.”

If the Red Wings want to make changes, there will be an opportunity to do so.

Kyle Quincey is an unrestricted free agent who isn’t expected to return. In a thin free agent class, a steady player such as Quincey could attract a bigger payday than the Red Wings want to pay.

Danny DeKeyser and Alexey Marchenko are both restricted free agents but unlikely to go anywhere — both are building blocks for the future.

That leaves Niklas Kronwall, Jonathan Ericsson, Mike Green and Brendan Smith, with Smith the likeliest trade bait, a relatively young player who still has potential.

Kronwall battled through a knee injury that affected his performance throughout the season, while Ericsson and Green both underachieved.

Then, there’s three defensemen from minor league affiliate Grand Rapids on the horizon.

Xavier Ouellet, Ryan Sproul and Nick Jensen will all be out of options and must be exposed to waivers if they’re sent back to Grand Rapids after training camp. Ouellet will likely stay with the Red Wings, the organization confident he is ready for the NHL The fate of other two is still to be determined.

General manager Ken Holland said he will explore the trade market and free agency aggressively this summer to improve the roster.

“We’ve got good young players,” Holland said. “Do we have stars? I don’t know. I have to watch. We’ve got to draft, got to develop. We’ve got to explore free agency. We’ve got to change to the mix a little bit.”

And that means Quincey likely will be let go, though he formed an effective pair with DeKeyser for most of the last two seasons.

Quincey, 30, made no secret he’d prefer to stay with the Red Wings, the organization that drafted him.

“Two years ago I didn’t know anything until July 1 (when the free agent market begins),” said Quincey, who re-signed with the Red Wings on a two-year deal. “I’m assuming it’s probably going to be the same thing. If Kenny offers me something I’d love to come back. We love it here. But if not, July 1, we’ll see what happens.”

But Quincey sensed that change could be in the air toward the end of the season.

“I’ve been thinking that for a while and (I was) just kind of soaking in,” said Quincey on locker clean out day. “Philly, that game, with the uncertainty of the playoffs, I was really soaking in that game.

“A veteran in Colorado (when Quincey played with the Avalanche) told me ‘we’re in the business of winning’. Teams that win stay together.

“Everyone keeps talking about change.”

Cast of characters

Danny DeKeyser

Age: 26

Contract: Restricted free agent

Statistics: 78 games, 8 goals, 12 assists

Comment: Cornerstone for the future.

Jonathan Ericsson

Age: 32

Contract: Ends 2020, $4.25 million per year

Statistics: 71 games, 3 goals, 12 assists

Comment: Has regressed the last two seasons.

Niklas Kronwall

Age: 34

Contract: Ends 2019, $4.75 million per year

Statistics: 64 games, 3 goals, 23 assists

Comment: Coming off worst season of his career.

Alexey Marchenko

Age: 24

Contract: Restricted free agent

Statistics: 66 games, 2 goals, 9 assists

Comment: Young player the Red Wings will be counting on heavily next season.

Kyle Quincey

Age: 30

Contract: Unrestricted free agent

Statistics: 47 games, 4 goals, 7 assists

Comment: Red Wings will look to upgrade his spot.

Brendan Smith

Age: 27

Contract: Ends 2017, $2.75 million per year

Statistics: 63 games, 3 goals, 12 assists, 15 points

Comment: On a roster with few trade pieces Smith is one, though they like his attitude, physical edge.

Xavier Ouellet

Age: 22

Contract: Restricted free agent

Statistics: 5 games, 0 goals, 1 assist

Comment: Will finally get his first, prolonged NHL audition next season.

Mike Green

Age: 30

Contract: Ends 2018, $6 million per year

Statistics: 74 games, 7 goals, 28 assists

Comment: Free agent acquisition was, overall, a disappointment.