Less than 18 months have passed since Mikel Arteta played a pivotal role in convincing Pierre-Emerick Aubameyang to sign a contract extension with Arsenal. The striker was coveted throughout Europe at the time, with Barcelona, Inter Milan and even London rivals Chelsea sensing an opportunity to snatch away the Gunners' prized forward as negotiations dragged on for months.

Sources have told ESPN that Arteta was vital in securing the breakthrough, developing a close relationship with the striker's father, Pierre, and talking a club forced into staff cutbacks elsewhere due to the COVID-19 pandemic into spending a huge sum on one player.

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He argued that as captain, Aubameyang was to be the figurehead of a new era, and as such, he warranted a new deal starting at £250,000-a-week with plenty of incentives on top -- if the vision of success being laid out was realised. Yet in the final days of 2021, Aubameyang finds himself an outcast. He was stripped of the captaincy after his manager publicly questioned his "commitment and passion" for the cause, and sources claim there's a genuine possibility he could leave the club during the January transfer window.

How did it come to this?

Arsenal felt they were making a huge statement in convincing Aubameyang to stay last summer.

They remain a club desperate to prove years of gradual stagnation and decline are behind them, and that a young, unproven but driven manager has the dynamism required to return the Gunners to former glories. Their FA Cup win in August 2020 pointed firmly in that direction. Beating Manchester City in the semis, and then Chelsea in the final, proved it was no fluke: Arsenal were everything that they had so often struggled to be in games against fellow members of the traditional "Big Six" in playing compact, courageous and clinical football.

Aubameyang's role at the top end of the pitch was everything. Arteta's squad was short on creativity, and as a team, mustered seven shots on target in those two games. Aubameyang scored with four of them, two each against City and Chelsea, to cement his status as a big-game player, leading by example when it mattered most.

Talks over a new contract were advancing by this point, but any lingering doubt on either side was removed with the tangible return of a trophy. The club trusted Arteta's judgement implicitly, and here he was, advocating for another big decision. Confirmation of a three-year contract officially came on Sept. 15, 2020 -- just a few days after the formal paperwork was signed -- but in truth, the agreement had been reached a few weeks earlier.

Sources have told ESPN that one reason for the delay was that the club's then-new head of brand marketing, Adam Gardiner, was keen to make a big splash on social media. Lengthy internal conversations followed about how to maximise exposure from this opportunity, perhaps moving away from the conventional club website interview in favour of Aubameyang hosting an Instagram live to reveal the deal. Eventually, he did just that at Emirates Stadium, before the club released an accompanying video in which he spoke about his dream of becoming a legend in north London.

Yet now he's facing comparisons with Mesut Ozil as another once-celebrated superstar whose focus and application are in question, viewed by some as a liability, and is sat on a huge contract that makes him harder to shift.

The bare numbers support the popular naked-eye view that Aubameyang's form has declined since signing his contract. Up to Sept. 15 last year, Aubameyang had scored 72 goals in 111 games since signing for a then club-record fee of £56 million from Borussia Dortmund in January 2018. Since then, he has netted 20 times in 52 games. That return isn't dreadful in isolation, but while a debate has often hinged on whether he should play through the middle or off the left, the bigger uncertainty around Aubameyang has been his off-field conduct.

Arteta stripped Aubameyang of the captaincy for what he described as the Gabon international's "latest disciplinary breach." Sources have told ESPN that this was in reference to his late return from France for a visit with his ill mother, a trip for which he was given special dispensation at a time when overseas travel was being restricted due to rising coronavirus cases in the United Kingdom. Aubameyang was consequently a coronavirus risk upon his return, though this wasn't the reason for his demotion.

It was simply one occasion too many on which he bent rules the entire squad are expected to follow, and rules as captain he's supposed to support, and perhaps even enforce.

One of the biggest issues at Arsenal has been the erosion of a professional, ruthless culture. It dates back to the latter days of Arsene Wenger's reign and can be reflected in his choice of captains, who were sometimes selected on the basis of their contractual status as much as any genuine leadership traits. Cesc Fabregas and Robin van Persie were given the armband in the hope it would somehow engender fresh loyalty to resist moves elsewhere. In both cases, the strategy failed.

The captain's authority was diluted further when given to Thomas Vermaelen, Arteta himself as a player and Per Mertesacker, all of whom spent more time injured on the sidelines than in the first team.

Laurent Koscielny was skipper when he went on strike and forced through a move to Bordeaux on the eve of the 2018-19 season. His successor, Granit Xhaka, was stripped of the armband after telling his own fans to "f--- off" as they booed him for taking too long to walk off the pitch when being substituted in a home game Arsenal were drawing against Crystal Palace.

For a long time, the bar felt pretty low. Arteta has tried to change that, instilling a greater work ethic and renewed professionalism. Aubameyang has not had one major act of insubordination but a series of minor indiscretions that added up to this week's decision. With the club continuing to wholeheartedly trust in Arteta, technical director Edu and chief executive Vinai Venkatesham were unambiguous in their support.

Aubameyang's timekeeping is notoriously poor. Last year, he was fined for missing a COVID-19 test before a Europa League fixture. In February, he was "reminded of his responsibilities" after footage emerged of Aubameyang receiving a tattoo despite strict coronavirus regulations. A month later, he was dropped for the north London derby against Tottenham hours before kickoff after reporting late for a team meeting on the day of the game.

Sources have told ESPN there were other similar incidents where Aubameyang arrived late for various club duties.

It is also claimed that Aubameyang does little by way of organising team bonding events, usually a captain's responsibility. On at least one occasion, he has been known to arrange a team meal but then pull out at the last minute, yet he remains a popular figure. It is worth remembering Aubameyang won the captaincy as a result of a players' vote, and many find his gregarious character highly engaging.

Sources claim Aubameyang likes to fill his house with many people in normal times, a habit that represents a difficult test of Arsenal's coronavirus protocol, but he does it all with charm and a wide grin. Chelsea boss Thomas Tuchel worked with Aubameyang at Dortmund, and back in May he summed up the fine line he often walks.

"I think he did not miss one single training in two years," Tuchel explained. "Maybe he arrived five minutes late on the training ground, that can happen with him! But if he does this, he is in a hurry, he excuses, he feels sorry, he has still a smile on his face."

Tuchel then joked: "When we wanted him to be on time, we told him the meeting was 10:45 a.m. when the meeting was 11 a.m., so there was a good chance he would be there with everyone else."

The joke eventually wore thin for Arteta, who admitted when he took over that he initially had reservations about Aubameyang after hearing those rumours from his Dortmund days before being won over.

Arteta insisted last week that the decision to strip Aubameyang of the captaincy would have been the same no matter what level of form he was in, but there is no doubt that demoting him is an easier call these days given his reduced output. He was told in face-to-face meetings, first with Edu and Venkatesham and then with Arteta; the next question is whether there is a way back.

Sources have told ESPN that Aubameyang returned to training away from the rest of the squad last week. Arteta has point-blank refused to say whether Aubameyang's Arsenal career is over or even when he will be considered for selection again, but the Africa Cup of Nations next month provides a break for both to mull over their options.

The tournament begins on Jan. 9, and Aubameyang is expected to join up with Gabon at the beginning of the month, and the distance might lend fresh perspective or reinforce a notion they are better off apart for good. Sources say as things stand, the latter is more likely. Gabriel Martinelli is certainly seizing his opportunity, scoring a brace at Leeds on Saturday in addition to his goal against West Ham four days earlier, which bore hallmarks of Aubameyang at his best, drifting in off the left to score right-footed. His drive, intensity and end product is an awkward comparison for Aubameyang at present.

It remains to be seen whether Barcelona -- or perhaps Juventus, who have emerged as a possible option in recent days -- are willing to return for Aubameyang and offer him a way out, or whether another club will take a punt on a striker earning a huge wage who turns 33 in June.

The speed of his fall from grace will weigh on their minds too.