David Quinn came into his postgame press conference with his best frown on, the tassels on his loafers audibly bouncing as the Rangers coach trudged to the lectern and tried to explain his team’s listless 4-1 loss to the Golden Knights at the Garden on Monday night.

“I didn’t like our mentality,” Quinn said, as his team had its five-game points streak (4-0-1) broken with quiet performance on a lazy, snowy Manhattan evening. “We were way too risk-oriented. We just didn’t play a very sound, structured game. I thought we really fueled their offense.

“It was really too much of a pond-hockey feel in a lot of ways.”

That has been Quinn’s refrain — “pond hockey” — when his Rangers (13-10-3) get too loose, which happens far too often. They have seen the fruits of playing smarter, simpler hockey, having gone 10-4-2 in the previous 16 coming into this one.

But when they start turning the puck over at blue lines, when they start allowing odd-man rushes by the bushel, when either goalie is left out to dry — in this case, Henrik Lundqvist — it gets the heat rising to Quinn’s head.

“I’ve mentioned this before, where we’ve been good, or really bad [defensively],” Quinn said. “It’s a mindset, and something we’ve got to completely buy into — that night in and night out, we have to be way more committed to playing the right way and playing defense.

“I didn’t think our ‘D’ corps was really all-in from a defending standpoint. We were way too offensive driven.”

These Rangers are young, and they may have gotten a little ahead of themselves with the nice little run they put together. But the Golden Knights (14-11-4) jumped on them for two goals in the opening 3:50 of the game, both from Alex Tuch. The second came on a power play that precipitated another low point for the Rangers special teams — 0-for-2 on the penalty kill and 0-for-6 on the power play.

How quickly the two shorthanded goals, among an 8-for-8 on the man-down against the sputtering Devils on Saturday in Newark, faded into memory.

“In the end, it comes down to special teams,” said Lundqvist, who made 28 saves on 32 shots, really only wanting back the breakaway to Reilly Smith at 4:44 of the second period that made it 3-0. “We’re not getting it done on the PK. … You saw it the other day, we won that game on the PK. As a goalie, that’s a big part. I need to find a way to make that extra save on the PK. It doesn’t matter if they’re making good plays or not.”

henrik lundqvist rangers golden knights
Henrik LundqvistCharles Wenzelberg/New York Post

Lundqvist had no chance on the fourth one, a terrific cross-crease feed from Cody Glass to Max Pacioretty to make it 4-0 at 6:20 of the second. The Rangers didn’t quit, getting a nice deflection from Brendan Lemieux at 15:15 of the second to make it 4-1.

But the hole was just too deep, and the Rangers tried to dig their way out of it with finesse rather than with simplicity.

“Definitely was not the start we were looking for,” Brady Skjei said. “We were told we had 13 scoring chances [against] in the first 10 or so minutes. That’s not the way you want to start. … We took a few too many chances here and there, and couldn’t put it in the back of the net.”

This was far from one of those disasters that has pockmarked the Rangers season thus far. It didn’t get out of hand, and the Rangers didn’t quit. If they had buried a couple chances, the entire complexion of the game could have changed.

But they didn’t, and now they’re stuck with another lesson in how not to start, how not to come back — and how to agitate their coach.

“We weren’t ready to play at that pace to start,” Quinn said. “We looked sluggish right from the get-go.”