Not Cesc Fàbregas from Barcelona. Not Patrick Vieira from AC Milan. Not even Thierry Henry from Juventus, for a paltry £11m. No, those who walk Arsenal’s corridors of power instead privately concede that the greatest signing made during Arsène Wenger’s 22 years in charge was Sven Mislintat, appointed as head of recruitment from Borussia Dortmund in November 2017 and seen as nothing short of vital to the future of the club.

Opportunistically lured from Dortmund after a bitter falling-out with then head coach Thomas Tuchel, Mislintat arrived in north London with a reputation as one of Europe’s foremost player recruitment experts. During his decade at the Westfalenstadion he personally oversaw the signing of players who would go on to form the club’s ‘golden generation’, winning back-to-back Bundesliga titles and reaching the 2012/13 Champions League final under Jürgen Klopp.

But now, little over a year after joining Arsenal, Mislintat has quit the club having decided that recent backroom developments have made his position untenable. After arriving to such fanfare, Mislintat has found himself increasingly marginalised since the exit of chief executive Ivan Gazidis, with the club instead lining up former player Edu for the sporting director role he had craved.

In the words of one agent who has worked closely with the club: “Arsenal pulled off the true transfer coup of the century when they recruited Mislintat — and have blown it already.”

Mislintat’s Arsenal career began encouragingly enough. Appointed by Gazidis, his new colleagues found him to be a demanding but impressive character, possessing the kind of strategic eye that had been so sorely missing during the final few seasons of Wenger’s troubled reign. He hit the ground running: playing a crucial role in the club-record signing of Pierre-Emerick Aubameyang for £56m, and helping to convince Henrikh Mkhitaryan to join Arsenal as part of the deal taking Alexis Sanchez to Premier League rivals Manchester United.

Ranking every Arsenal player signed since Sven Mislintat's appointment Show all 9 1 /9 Ranking every Arsenal player signed since Sven Mislintat's appointment Ranking every Arsenal player signed since Sven Mislintat's appointment Ranking every Arsenal player signed since Sven Mislintat's appointment We rank every Arsenal player signed since the arrival of Sven Mislintat from Borussia Dortmund. Getty Ranking every Arsenal player signed since Sven Mislintat's appointment 8. Stephan Lichtsteiner 5/10. Signed on a free transfer from Juventus, although far too slow to be relied upon as a regular first-team option. AFP/Getty Images Ranking every Arsenal player signed since Sven Mislintat's appointment 7. Konstantinos Mavropanos 6/10. The first signing made under Mislintat's tenure as head of recruitment. Was sent-off last season against Leicester, but still only 21 with plenty of potential. Arsenal FC via Getty Images Ranking every Arsenal player signed since Sven Mislintat's appointment 6. Sokratis Papastathopoulos 6/10. A reliable option at the heart of Arsenal's defence, but £17.6m was an awful lot to spent on a 30-year-old. Getty Ranking every Arsenal player signed since Sven Mislintat's appointment 5. Henrikh Mkhitaryan 6/10. Arrived at the Emirates as part of the deal taking Alexis Sanchez to Manchester United. Has impressed sporadically but is yet to look anywhere near his best. Getty Ranking every Arsenal player signed since Sven Mislintat's appointment 4. Bernd Leno 7/10. Forced to wait for his chance, but now Unai Emery's established number one. Has made the occasional mistake but settling in well. Action Images via Reuters Ranking every Arsenal player signed since Sven Mislintat's appointment 3. Matteo Guendouzi 8/10. Pound for pound, arguably Arsenal's best signing of the last two seasons. Already a regular aged just 19 and a snip at £7m. REUTERS Ranking every Arsenal player signed since Sven Mislintat's appointment 2. Lucas Torreira 9/10. Exactly the sort of player Arsenal have been crying out for years now. Not just a first-team regular, but utterly essential to how Emery wants to play. Getty Ranking every Arsenal player signed since Sven Mislintat's appointment 1. Pierre-Emerick Aubameyang 9/10. A fantastic signing, albeit for a hefty sum. Already has 24 goals in just 35 Premier League appearances and has developed a fine strike partnership with Alexandre Lacazette. Getty Images

Ahead of his first summer transfer window with the club, as Arsenal prepared to appoint their first new manager since 1996, Mislintat was tasked by Gazidis with identifying affordable transfer targets using the kind of analytical approach that had served him so well at Dortmund. And so Bernd Leno, Lucas Torreira and Mattéo Guendouzi were signed for a collective £52m — all becoming immediate successes — while Sokratis Papastathopoulos and Stephan Lichtsteiner were brought in to add steel to Arsenal’s backline.

Given Arsenal’s well-documented financial constrictions, it was a successful window, with Mislintat’s work not going unnoticed in the boardroom. “Clearly we need to make smart decisions around player signings,” managing director Vinai Venkatesham told the Independent at a club briefing in November. “And it is still very early days, but players like Torreira and Guendouzi already look to be a big part of our future.”

Yet behind the scenes, cracks were beginning to show. Sources close to the club say that new head coach Unai Emery — who Mislintat helped to appoint — has taken a far more active role in identifying transfer targets than Mislintat anticipated, especially considering the club’s new executive structure, which was designed to dilute the influence of the manager after so many years of autocracy under Wenger.

This month’s transfer window has also caused problems. Mislintat has a collective responsibility for identifying targets alongside Emery and head of football Raúl Sanllehí, who was promoted after Gazidis left for AC Milan. However, the club’s interest in out of favour Barcelona winger Denis Suárez is being driven not by Mislintat but Emery, who coached the player at Sevilla, and Sanllehí, who spent close to a decade working at the Camp Nou.

Although there has been no breakdown in Mislintat’s relationship with either Emery or Sanllehí, the latter’s preference for orchestrating transfers through his extensive network of contacts has jarred with Mislintat’s statistical approach. Arsenal’s inability to sign any new players this January because of a lack of funds — a policy that extends to the Under-23 and academy sides — has also proved difficult for Mislintat, who garnered the nickname ‘Diamond Eye’ in Germany for his ability to spot and sign talented young players from rival clubs.

Denis Suárez is Arsenal's primary January target (Rex Features)

One source tells The Independent that Mislintat has grown increasingly tired of “unfulfilled promises” at Arsenal, particularly since the club pressed ahead with plans to create a new sporting director role at the very top of the club.

Upon his appointment in 2017, Mislintat made clear to Gazidis his ambition of working in such a role after Wenger had stepped aside and the club had restructured accordingly. However, the elevation of Venkatesham and Sanllehí — who Mislintat now reports to — has seen the German become increasingly isolated.

Instead, the club’s former midfielder Edu has emerged as the outstanding candidate for the sporting director role, which will involve assuming responsibility for the various technical aspects of the club, including style of play, coaching practices and the academy intake. The Independent understands there have already been relevant discussions between the two parties, with Arsenal executives impressed with Edu’s work as the technical director of the Brazil national team.

Sources close to the club admit that the lack of forward planning afflicting their expensively assembled squad — Arsenal’s four highest earners play across just two positions, leading to Emery regularly leaving at least two out of his starting XI — also extends to the boardroom, particularly in the wake of Gazidis’ surprise move to the San Siro in September.

Ivan Gazidis left Arsenal for AC Milan (Arsenal FC via Getty)

Gazidis personally oversaw the appointments of both Sanllehí and Mislintat, as well as academy manager Per Mertesacker and Team Sky’s legal and commercial expert Huss Fahmy. Together, the men sit as just four footballing representatives on the club’s 15-man executive team. But there is a lingering suspicion that Arsenal simply saw who was working well elsewhere and appointed them — with little thought as to how they might work together. In the words of one agent with connections to the club: “There was no unifying vision. Steak is great. Apples are great. But who wants apple steak?”

Of the three people who initially interviewed Emery last summer, eventually championing him as Wenger’s successor, two have now left the club. Only Sanllehí remains. It is a remarkable turn of events considering how thoroughly Emery was vetted, with Mislintat’s departure coming at a particularly bad time for the club given the contract uncertainty currently surrounding players including Aaron Ramsey, Danny Welbeck and top-earner Mesut Özil.

Mislintat likely won’t have to wait long before finding a new position, with Bayern Munich particularly keen in recruiting him, having attempted so many times to lure him away from Borussia Dortmund. The Bundesliga champions are confident they can complete a deal before the end of the season, having already identified the 46-year-old as the ideal man to begin a complete overhaul of their ageing squad.