The Islanders gave up 2.9 goals per game this season, eighth-most in the NHL. Not all of that falls on the defensemen, but this was not a banner year for the team’s blue line corps.

It’s a group that likely will look very different next season, with the expansion draft looming next month, and with the recent re-signing of veteran Dennis Seidenberg, seven defensemen under contract for next season and two, Calvin de Haan and Adam Pelech, restricted free agents.

Add in a few promising prospects and the Islanders likely are looking to retool the defense from within while subtracting one or maybe two regulars from recent seasons. Here’s a detailed look at each Isles defenseman from 2016-17 and where this corps is headed.

All statistical information comes from the websites Corsica Hockey, Puckalytics, Hockey Analysis or the NHL’s site. Salary information from the Cap Friendly site.

Nick Leddy

81 games, 11 goals, 35 assists

advertisement | advertise on newsday

$5.5 million cap hit, signed through 2021-22

It was a tale of two seasons wrapped into one for Leddy, who had a fairly miserable first half under Jack Capuano and really thrived when Doug Weight took over. Capuano’s biggest mistake likely was keeping Leddy and Travis Hamonic paired through a rocky first few months when it became clear that pairing was not working.

Leddy played roughly 519 minutes with Hamonic this season and the two generated just 43 percent of the shots taken when on ice together. Leddy and Johnny Boychuk were the main pair with Weight behind the bench – Hamonic missed most of the second half with injuries, to be fair – and those two generated 51 percent of the shots.

Hamonic, as you’ll see below, had a truly miserable season. Leddy produced well at even strength – his 31 even-strength points were sixth on the team – and he was a mainstay on the top power-play unit, for whatever that was worth in a lousy season for the team’s power play.

It was suggested at some point during the Isles’ ugly first half that Leddy could be the trade chip that helped turn the team around. When Weight came in, he identified Leddy as the team’s second-most important player, behind John Tavares. With his unequaled skating skills, Leddy certainly improved the team’s transition play with Weight’s system tweaks and he will be hugely important going forward.

Travis Hamonic

49 games, 3 goals, 11 assists

$3.86 million cap hit, signed through 2019-20

Hamonic didn’t sugarcoat how he felt about 2016-17. He was referring to the various injuries – a broken thumb in November, a torn knee ligament in January and torn thumb ligaments in March – that cost him 33 games. He also could have been talking about the rough times he had on the ice in his seventh season, a surprising step back for a player the Islanders have a lot invested in, emotionally and structurally.

Hamonic’s relative Corsi percentage was -4.47, meaning the team generated nearly 4.5 percent fewer shots than it allowed when he was on the ice compared with when he wasn’t. Only 19 other NHL defensemen who played at least 40 games had worse percentages than that in 2016-17. For comparison’s sake, the best relative Corsi percentage for any Isles defenseman in 2015-16 was 1.86 – that belonged to Hamonic.

advertisement | advertise on newsday

“It wasn’t my best year but I don’t think the numbers reflect my season,” he said last month. “I’ve got to be better and I own that. I don’t think the numbers reflect how I feel, but I have to be better.”

The difficulty in evaluating Hamonic after such a lousy season comes with the expansion draft and the Isles’ desire to add scoring up front. After his tumultuous 2015-16, when Hamonic’s private plea to Garth Snow in training camp to be traded closer to his Winnipeg home for personal reasons was made public in November, followed by perhaps his best season as an Islander and the rescinding of that request in May, one would have thought that settled things for him.

But the lousy, injury plagued season, coupled with the Isles missing the playoffs and needing to expose defensemen they might like to keep, means that these next few weeks will be interesting for Hamonic. Snow fielded plenty of offers for Hamonic that didn’t fit the Isles’ needs last year. Would he revisit some of those teams’ requests now? The Oilers won’t have Andrej Sekera for most of next season and they were the hottest on Hamonic last year.

With Matt Martin’s departure last summer, Hamonic has become the emotional core of the Isles. He injured his thumb late in the season in a fight in Philadelphia trying to give his team a spark. Perhaps all that intangible talk pales beside the stark numbers — his appealing cap hit being tops among them — and Snow needs to be colder and more calculating coming off a lost year.

A lot to think about on all sides over the next month or two.

advertisement | advertise on newsday

Johnny Boychuk

66 games, 6 goals, 17 assists

$6 million cap hit, signed through 2021-22, no-move clause

A bounce-back year of sorts for Boychuk, who certainly didn’t have a bad 2015-16 but definitely was stronger in 2016-17 – and very much missed with an ankle injury that cost him nearly all of March. The Isles were 5-7-0 without him in that crucial stretch.

Boychuk had the D corps’ best relative Corsi percentage this season among the regulars at 1.66. He played primarily with Leddy or Thomas Hickey and, while better with Leddy, was consistent with both in terms of shot generation and suppression. Consistency was hard to come by for the Isles this season but Boychuk was steady all year, which is a high compliment.

Boychuk is 33 and he plays a style guaranteed to cause physical breakdowns — blocking shots and engaging physically with opponents will do that. He also is the only defenseman with a no-move clause, meaning unless he agrees to a one-time waiver, the Isles have to protect him in the expansion draft.

“I don’t need to, I don’t think,” Boychuk said last month on breakup day as to whether he’d have to consider waiving his no-move. “I like it here, I signed here for a while. I don’t see myself being asked that.”

That doesn’t mean it hasn’t come up since or that it won’t in the weeks to come before the protected list is submitted. But Boychuk’s quote is pretty indicative of how players with no-move clauses feel. Even if the thought of being claimed at his age and with his contract seems farfetched to the rest of us, the players typically feel they’ve earned the no-move clause and they don’t want to even entertain the idea of uprooting the family to go elsewhere.

So there’s the rub for Snow.

Thomas Hickey

76 games, 4 goals, 16 assists

$2.2 million cap hit, signed through 2017-18

“Steady as she goes” has to be Hickey’s motto. How else to explain identical even-strength Corsi for percentages (48.1) from 2015-16 to 2016-17? That number, as well as the 0.74 relative Corsi for percentage, doesn’t scream “elite defender,” but with the overall numbers this group posted last season, it’s quite acceptable.

The 28-year-old Hickey has certainly shown a flair for the dramatic in his five seasons with the Isles, with his third and fourth overtime winners among his four goals – his OT winner in Nashville in the final week could have been the biggest goal of the Isles’ season had they squeaked into the playoffs. Lots of fans cringe at seeing the diminutive Hickey get bodied around, but he is a more-than-competent defender and skater.

He will not be protected in the expansion draft, however. Between Leddy, Boychuk, Hamonic, Ryan Pulock and Calvin de Haan, there’s already no room for one of those, so Hickey surely will be left exposed should Vegas be interested.

A lot depends on what moves Snow makes before the expansion draft and the fact Hickey is only signed through next season makes him a bit less appealing to be picked. If it shakes out that the Isles make two moves on defense and Hickey is left as the mainstay third-pair defenseman, Weight and Snow figure to be pleased.

Calvin de Haan

82 games, 5 goals, 20 assists

Restricted free agent

By any measure this was de Haan’s best season with the Islanders. His relative Corsi percentage of 0.6 won’t break any records, but given the minutes he logged this season – nearly 1,000 of them with Seidenberg as the defense pair opposing teams tried to take advantage of – de Haan’s season was a decent success.

He was injury free, another important milestone. He had career bests in the main statistical categories, was top-five in the league in shots blocked and continued to be the funniest Islander on Twitter. All good things.

Now, the hard part. Do the Isles sign him before the expansion draft and hope that new contract is prohibitive or do they wait and hope Vegas isn’t interested in negotiating a long-term deal with one of their newly plucked players?

Either way, de Haan is an attractive commodity. He’s 26 and already in that mode of dependable, middle-to-bottom pair defenseman. Seeing some of the lesser-known defensemen shining in the conference finals, having a reliable player like de Haan around long term isn’t a mistake.

Adam Pelech

44 games, 3 goals, 7 assists

Restricted free agent

The 22-year-old Pelech stepped up in responsibility and minutes with the Isles this season and did OK – his relative Corsi percentage was -1.68, better only than Hamonic’s, and every defenseman he was paired with this season had better Corsi numbers without him save for de Haan, who played only 85 minutes as Pelech’s partner.

So perhaps OK doesn’t describe it, but there’s a funny dynamic at work with Pelech. He’s a comfortable skater and defender, he doesn’t take a ton of risks but the underlying numbers aren’t really there yet. It’s only been 53 games over two seasons, so none of this is set in stone.

But there will be changes to this D corps and guys such as Devon Toews and Parker Wotherspoon, not to mention Pulock, will be pushing for spots in the coming seasons. Pelech needs a new deal, which shouldn’t be an issue, but he also needs a spot and that may be determined by what the group of young defensemen does in training camp.

Scott Mayfield

25 games, 2 goals, 7 assists

$625,000 cap hit, signed through 2017-18

Perhaps the most eye-opening Isles defenseman this season. Like Pelech, there’s a small sample size, but Mayfield showed a lot more this season than he did in either of his previous two NHL stints — way more even than he did in last season’s training camp, when he was waived early on and there was no hint of a claim coming from another team.

Mayfield played half his NHL minutes last season with Hickey and they were a pretty strong pair – over 53 percent Corsi for when on together. Mayfield had some minutes with Leddy as well and they were over 55 percent. The big, 24-year-old defenseman showed really good mobility and decision-making when he played for the Isles last season, a far cry from some of his overzealous moves to be physical in prior years.

If he can keep this up, the Isles may have themselves a solid back-end defenseman who isn’t shy about jumping into the play or into the fray.

Dennis Seidenberg

73 games, 5 goals, 17 assists

$1.25 million cap hit, signed through 2017-18

That the Islanders signed Seidenberg in the middle of training camp elicited a few groans from the gallery. Snow does have a long history of bringing in veteran defensemen hitting the down slope of a solid career, to wildly varying results (Mark Eaton, Steve Staios, Lubo Visnovsky, Marek Zidlicky), so this one was viewed with trepidation.

Now that Seidenberg, who turns 36 in July, is already signed for a second go-round, the gallery is chirping a bit louder. Not because of what Seidenberg did this past season, which by any measure was pretty good – he had his highest point total since 2011-12 and his Corsi percentage numbers, while on the wrong side of 50, were still better than he had his last few seasons with the Bruins and those teams were possession monsters, unlike the Isles this past year.

Everyone understands that the Isles would be better off with younger defensemen working through mistakes to reach their potential than a mostly reliable 36-year-old. But the reality for Snow and Weight is that they saw too much underachieving from their young defensemen last training camp to hand two of them spots on opening night this coming year.

So Seidenberg – who happens to be a rock-solid guy off the ice, in the mold of the soft-spoken but always direct Frans Nielsen – will be back in some role. Might be third pair again, might be someone who rotates in and out.

IN THE PIPELINE

Ryan Pulock

55 games, 15 goals, 31 assists (with AHL Bridgeport)

The 22-year-old with the big slapshot got all of two shifts with the Isles this season, leaving with a broken foot and never returning. After his strong turn in the 2016 postseason, many expected he’d be a top-six player for good this year and it’s puzzling that it never happened, even after Hamonic and Boychuk went down late in the year and the Isles could have used a right shot and someone to wake up the moribund power play.

But he’s still part of the team’s future, either as a very enticing trade chip or someone to compete yet again for a regular role. He’s done all he can do in the AHL, where he’s posted 39 goals in three seasons. The biggest question for Pulock is durability, with a major injury shelving him every year.

And yes, he does need to be protected in the expansion draft. Don’t ask again.

Devon Toews

76 games, 5 goals, 40 assists (with Bridgeport)

The 108th overall pick in 2014 has turned out, so far, to be a promising prospect. Toews made the transition from Quinnipiac and the short NCAA season to the AHL seamlessly, tying for ninth in the AHL in scoring among defensemen. He’s already 23 so it wouldn’t surprise anyone that he’s ready for a shot with the Isles at some point next season.

Parker Wotherspoon

69 games, 10 goals, 56 assists (with WHL Tri-City)

Another fourth-round pick, Wotherspoon has the Isles’ development team excited. He had 182 points in four seasons in the wide-open Western League, but he has some bite to him that should serve him well in the AHL next season. He turns 20 in August so there’s no rush to get him to the NHL just yet.