The Islanders never looked like the Oilers’ equal on Saturday, but for almost the first half of the game, you could at least say they were holding their own, defending hard and giving a good account of themselves.

By the end of what became a penalty-laden, 4-0 blowout defeat, that cheery viewpoint had evaporated. Faced with an opponent who wasn’t cowed in the face of some tight checking and high-effort defense, the Islanders imploded first.

They were playing with fire from the start, losing Emil Heineman 2:22 into the game after a needless knee-on-knee hit to Isaac Howard that got him ejected and could get him suspended — a scenario that would leave the Islanders scrambling for replacement given the injuries they’re dealing with in the NHL and the way their AHL club in Hamilton is struggling.

The last 12 minutes of the second period were when the high-wire act — 11 forwards, playing right up to the physical line and trying as hard as they could to keep Matthew Schaefer matched up with Connor McDavid and friends — broke down.

The Islanders made their first big defensive error of the afternoon when both Tony DeAngelo and Logan Stanley went into a battle against Kasperi Kapanen, leaving Ryan Nugent-Hopkins free to come down the slot and put the Oilers ahead when Kapanen won the puck.

Just 1:08 later, at 9:50 of the second, the McDavid line got cooking when Vasily Podkolzin was left alone at the back post to finish an easy pass across from Leon Draisaitl.

Especially on a day when the Islanders’ power play had no juice, even that looked like it might be the ballgame. 

Pete DeBoer’s club had defended with gusto, but rarely got on the cycle or forecheck, and never held the puck for shifts at a time against an Edmonton club that has a deeper, faster well of talent. The Islanders’ first shot didn’t come until the 8:08 mark of the first, and they had next to nothing high-danger all afternoon.

Tristan Jarry got the shutout, but for holding the Islanders scoreless, the Edmonton netminder had awfully little impact on the game itself, so woeful were the home team’s attempts at offense. 

It is afternoons like this when Mat Barzal’s endless absence is felt the most. The Islanders just didn’t have the creativity to go create something from nothing.

Nugent-Hopkins got on the board a second time at 18:26 of the second, scoring off a McDavid backdoor feed after Schaefer was called for holding No. 97. It was a ticky-tack call, and in tandem with the goal being scored, Scott Mayfield took a 10-minute misconduct for getting into it with Kapanen.

Schaefer, normally so composed, had taken a second penalty before the period was over too — and was as openly unhappy with the referee about it as you’ll ever see him.

That sentiment on the Islanders’ bench only grew when Anthony Duclair was whistled for interference in the third, bringing the total to seven penalties, with the best power play in the land getting six chances and 9:51 to go to work.

If that’s a winning recipe, then Saturday wasn’t Halloween but Opposite Day.

Edmonton added a fourth when Mathieu Joseph scored into an empty net with just under three minutes left.

As long as they have this many injuries — the pregame update, by the way, was that Ryan Pulock was seeing the doctor, with no changes to the statuses of Calum Ritchie, Matias Maccelli or Barzal — it is going to take a near-perfect effort for the Islanders to beat teams with this much offensive firepower.

To their credit, the Islanders had that on Thursday night in Minnesota, and got out with an overtime win against the Wild. But they won’t have their A-game every time.

Saturday was the stinging reminder.