EDMONTON — A 6-5 overtime loss to the Boston Bruins underscored another need for the Edmonton Oilers as the trade deadline quickly approaches.

The absence of star Ryan Nugent-Hopkins due to illness on Wednesday forced others to fill in for him up the lineup, stretching the Oilers’ forward depth to a point it couldn’t manage.

“As a coach, you always have an idea of where guys should be slotted and who they should be playing with,” bench boss Kris Knoblauch said.

The obvious shining light was Warren Foegele capably replacing Nugent-Hopkins as the No. 1 left winger by scoring twice as part of an ice-tilting performance by the top trio and best defence duo.

The Oilers out-attempted the Bruins by a 4-1 ratio with Foegele, Connor McDavid, Zach Hyman, Mattias Ekholm and Evan Bouchard skating at five-on-five, per Natural Stat Trick.

“He definitely stepped up into that,” Knoblauch said.

“He’s a guy who, when he gets an opportunity to move up in the lineup, he makes the most of it,” added Hyman.

Peel the layers of the onion and things aren’t as pleasant.

Those front-line efforts were wasted as part of a valiant comeback that earned them just a single point in the standings instead of two because of Charlie McAvoy’s goal 3:10 into the extra period.

A big reason for that half prize was because the bottom six — sans Foegele and devoid of other top-six substitutes Ryan McLeod or Corey Perry — was left in a weakened state without Nugent-Hopkins.

The scaled-down third and fourth lines struggled mightily — at least until Mattias Janmark tapped in a loose puck in the third period that Bruins goalie Jeremy Swayman left sitting in the crease.

They were caved in for much of the first 40 minutes and were on the ice for Boston’s third and fourth goals. With the Oilers trailing 4-2 as the second period wound down, Knoblauch was forced to revamp most of his lines — something he’s done on so many occasions of late.

In some respects, this game isn’t the best example on which to judge the Oilers because, well, of course things are always to be challenging with Nugent-Hopkins resting instead of playing.

Again, it’s not like it was all bad.

Foegele was outstanding. The Oilers out-attempted the Bruins 40-8 and outscored them 3-0 in his 15:45 five-on-five minutes, per NST. He scored both his goals from the blue paint.

McLeod was driving to the net early. Perry, who replaced McLeod next to Leon Draisaitl and Evander Kane, got the Oilers back to level terms for the first time in the third period with a goal off a rebound.

“That’s not an easy hole to fill,” Perry said of adjustments needed without Nugent-Hopkins. “But I thought guys were in and out of that spot, and everybody found their way.”

Maybe so. But their inclusions further up weakened the bottom half of the forward ranks as part of an atypical Oilers lineup.

That’s what makes it apt to analyze Wednesday’s loss.

The Oilers played a perennial powerhouse, the type of team they’re going to have to beat in a seven-game series late in the playoffs — as injuries tend to mount — if they want to win it all.

The absence of one regular — even a key one with Nugent-Hopkins — can’t affect this group this badly.

“We missed him,” Knoblauch said. “But throughout the year, you’re going to be missing some of your better players.”

Look at the Bruins. Hampus Lindholm, one of their top blueliners, missed Wednesday’s game and is out long-term. Matt Grzelcyk, another top-four rearguard, played just 35 seconds against the Oilers after a McLeod trip sent him crashing into the boards.

The Bruins still won despite missing Lindholm and Grzelcyk and playing with five defencemen almost the entire night.

Foegele’s fourth multi-goal outing of the season, to say nothing of Perry’s third-period goal after being elevated, was downgraded in defeat.

“Any time you have to raise somebody and move him up a line, usually that player can do it for a short period of time,” Knoblauch said. “But you do miss that depth making it more difficult (for the other team), especially tonight when we were at five defencemen for pretty much the entire night.”

It’s not like the non-McDavid-line forwards — namely the ones lower down the lineup — were the only problem.

The penalty kill allowed yet another goal and has now failed to do its job on 11 of the Oilers’ last 24 short-handed instances.

Stuart Skinner allowed six goals on 35 shots. The Brad Marchand short-side goal off the rush in the second period was the worst of the lot.

And it must be mentioned that the second defence pair of Darnell Nurse and Cody Ceci had a rough night.

Though Ceci’s spot at No. 4 defence is a prime and worthwhile position to be upgraded ahead of the March 8 trade deadline, Wednesday’s game highlighted the forward issue with RNH out of commission.

“Nuge is an unbelievable player and a huge part of the team. He plays in every facet of the game,” Hyman said. “You can’t replace a guy like that.”

That Nugent-Hopkins is sidelined only temporarily just emphasizes the point more.

Add Nugent-Hopkins and acquire another scoring winger — someone designed for the top six — and all of Foegele, McLeod and Perry can play as three of the Oilers’ last half-dozen forwards.

Take Nugent-Hopkins out and, without an impactful trade, two of those guys need to take on roles that leave the rest of the group severely lacking.

That’s what happened on Wednesday against the Bruins, a midweek game in the dog days of the season.

That can’t be what happens in a pivotal playoff game several weeks from now.

(Photo: Codie McLachlan / Getty Images)