There was proper solemnity and concern from the Rangers on Tuesday night following their staggering 4-3 Garden loss to the Islanders, in which they held a 3-1 lead into the third period following their most urgent first 40 minutes since opening night.

But of all the observations inside the postgame room, the most pertinent came from Adam Fox, who said: “We can’t rest on last year. We can’t say ‘We did that last year.’

“It’s been the same thing. We bring it for 40 or 30 or 50 [minutes]. We have to right the ship here.”

No one cares at this point about the 2021-22 Rangers’ run through May into mid-June. That seems as long ago as their last Stanley Cup. That group no longer exists. This 2022-23 team, which entered the season carrying expectations created by that team last season, hasn’t been able to come close to meeting that unenviable challenge.

At this point, though, that should be the last of anyone’s concerns. The Rangers haven’t been able to meet minimal expectations. They have established nothing as a unit. The Blueshirts are fraying, having won just three of their last 10 games (3-4-3) and now confronting a stretch in which they will play six of their next seven games on the road.

“I can’t pinpoint any one thing but I think we were sitting back too much and were trying not to lose,” said Vincent Trocheck, whose power-play backhand from his knees had given the Rangers a 3-1 lead at 13:47 of the second period. “I’m slightly concerned, but I don’t think this is a personnel thing. I believe in the group. I know what we’re capable of.”

If so, then Trocheck might be one of a small group. The fact is, we don’t quite know what this group is capable of 14 games into the season. The Blueshirts played fast and hard through the first two periods. They were physical and on the puck in forcing the step-behind Islanders to take four minor penalties within a span of 11:59 bridging the first two periods. Igor Shesterkin was sharp in goal.

But it all turned when the Islanders’ Adam Pelech wristed one through from the slot 14 seconds into the third period, completing an entry and a play below the goal line without much opposition. From that moment on, the Rangers seemed to be clinging to life, trying to will the clock to move faster. It did not.

Inevitably and indubitably, the visitors — 7-1 in their last eight and 9-5 overall — tied it on Brock Nelson’s power-play one-timer at 12:46 with Filip Chytil in the box for hooking. It was not as much that the Islanders took over the third period as that the Rangers yielded it by default.

It surely did not help matters when referees Brandon Blandina and Kelly Sutherland either missed or ignored Oliver Wahlstrom’s trip of Kaapo Kakko as the Rangers wing had possession along the defensive boards just two minutes after Nelson’s tying goal. It was only seconds later that the Islanders capitalized with an unmarked Anders Lee score from in tight at 14:30.

“It is very difficult for me to give an answer to explain this,” said Artemi Panarin, whose game continues to be pockmarked with too many turnovers and broken plays. “A few mistakes might be the difference. It has to change.”

The wholesale line changes effected by Rangers coach Gerard Gallant — who did not volunteer an opinion on the missed call, seemingly dancing around the issue — brought desired results through the first two periods.

Sammy Blais played his most imposing game. Alexis Lafreniere, on the left with Trocheck and a particularly noticeable Jimmy Vesey, played with moxie that is sometimes reserved for game against the Islanders. Vitali Kravtsov played with confidence, got through it unharmed, and was in the middle of things on Chytil’s score at 11:36 of the first. Chris Kreider went to the net and got a power-play goal off a backdoor feed from Panarin.

But it all came to a halt in the third period. There was maybe one glorious opportunity, Vesey’s breakaway that was denied by Semyon Varlamov with the Blueshirts up 3-2 at 7:42. Other than that, the team that went into the third period with a lead for the first time since Game 4 against the Ducks on Oct. 17, didn’t know what to do with it.

“[Not] playing 60, that’s a mental thing. We’re in a little bit of a rut. It’s a confidence thing,” Trocheck said. “We have a lot of young guys, but everyone can struggle with confidence. A lot of this game is mental. When you win games and get on a roll, that gives us confidence and a swagger.”

At this juncture, the Rangers have not earned swagger. There is nothing for them to fall back on, not even their reigning Vezina Trophy winner in the net.

Even on what appeared to be a good night, Shesterkin wound up with a save percentage of .846 by allowing four goals on 26 shots, the fifth time in 10 starts he was under .900. That’s for those who still need convincing that this is not last year.