LONDON -- The days of Arsenal leaving out their highest-paid player in the biggest matches were supposed to be over.

Mikel Arteta could only rue his team's naivety in conceding a stoppage-time equaliser to hand Slavia Prague a 1-1 draw and the advantage at the halfway point of this Europa League quarterfinal tie. Yet surely the bigger issue was his team's profligacy at the opposite end of the pitch, allowing a series of chances to pass them by on a night when clinical finishing could have masked another underwhelming performance.

There was undoubtedly some logic to Arteta's reasoning when explaining why Pierre-Emerick Aubameyang didn't start, highlighting the impact a late burst of pace could have on tired legs.

"There were some big decisions to leave some players out," said Arteta, "but we decided to play the team who had the best chance to start the game well and as well have some key players to change the game when we need it."

Their goal came from it. Aubameyang did well to control the ball and release fellow substitute Nicolas Pepe as Arsenal broke at speed. Pepe held his nerve well, lifting a smart finish over Slavia goalkeeper Ondrej Kolar.

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They had four minutes plus stoppage time to hold out, but couldn't. Lukas Provod's corner found its way to the back post where Tomas Holes stooped to head in at the back post.

Holes through the Arsenal defence -- sounds about right. Yet the Gunners were only in this position because of the profligacy that came before.

"What was missing is when you create big chances, you have to put them away," said Arteta. "And I think we made it much more than the result we got."

Bukayo Saka side-footed horribly wide when sent clear by Rob Holding. Willian hit the post with a free kick just after half-time. Alexandre Lacazette hit the crossbar when racing clear as Slavia defender Oscar Dorley was caught in possession as last man on the halfway line.

Lacazette then fired wide from Saka's back-post cross. Aubameyang missed a good chance of his own, producing a tame effort when Emile Smith Rowe's right-wing delivery came across him in the six-yard box.

Aubameyang perhaps had the excuse he wasn't fully attuned to the game, having been introduced less than a minute earlier, but then again he has been out in the cold for some time.

The 31-year-old was a peripheral figure in Saturday's 3-0 defeat to Liverpool, one member of the "little mafia" Sky Sports pundit Gary Neville suggested had looked utterly disinterested in Arteta's game plan. Arteta dismissed the severity of that characterisation in his pre-match news conference but his actions spoke louder than those words, dropping his captain for what is the most important game of the season to date.

He took Aubameyang off when losing to Liverpool and did so again at West Ham United. At London Stadium, Aubameyang was trudging around the pitch when Lacazette equalised, resembling a cheerleader rather than a talisman. Retaining club mascot Gunnersaurus for that task would have been a cheaper option.

Arsenal gave Aubameyang a three-year, £250,000-a-week deal for these moments, the games that define a campaign.

Mesut Ozil became a hugely expensive problem, viewed as a relic from a different era, but Arsenal's best moments under Arteta have had Aubameyang front and centre. He was the game-changer in the FA Cup semifinal and final, continuing a pattern of ruthless finishing to settle games of fine margins in their favour.

Aubameyang may not be in that same individual form at present -- and you have to wonder whether dropping the Gabon international for last month's north London derby has had a lasting effect -- but who do you want these chances falling to: the striker you are yet to decide whether to sell this summer or the one you moved heaven earth to tie down to a new contract less than a year ago?

At the very least, change should have come earlier than it did in these 90 minutes. Aubameyang, Pepe and Gabriel Martinelli injected fresh life into the home team as Slavia tired from a committed display in which they had chances of their own, Petr Sevcik firing wide from 16 yards when well placed in the box.

Arsenal's problems in managing matches, defending leads and showing sufficient resilience are well-documented, familiar problems. Aubameyang's role in the team is not, at least not until now.

All is not well. Aubameyang headed straight for the tunnel at full-time, exchanging words or glances with nobody. Asked afterward whether Aubameyang understood why he had been left out, Arteta was not exactly sympathetic in his response.

"Well, I cannot talk with everybody individually every week," he said. "We try to be transparent and communicate with the players as transparent as possible, for them to understand the role of the game that they have. When he came on he showed the right attitude."

Arsenal may well still find a path to the semifinals. They are alarmingly inconsistent yet still competitive against anyone when at their best.

Until recently, those performances invariably contained Aubameyang. Whether they still do remain to be seen.