Update, Wednesday, November 20, at 10:30 a.m. ET: José Mourinho was officially named as the new Tottenham manager on Wednesday.

The high-water mark for Tottenham Hotspur under Mauricio Pochettino came in May in Amsterdam. Giant-killing darlings Ajax had built a 3-0 aggregate lead over the London club with just 35 minutes and stoppage time to play in the second leg of their Champions League semifinal fixture when Brazilian winger Lucas Moura scored an unlikely second-half hat trick to put Spurs through on away goals.

The final strike came in the sixth minute of stoppage time, sealing one of the most dramatic comebacks in the history of the competition and cementing Spurs as not just a fashionable upstart club, but a genuine European power. And while the final itself was quite forgettable—Spurs conceded a first-minute penalty and sleepwalked to a 2-0 loss to Liverpool—Tottenham’s mere participation validated almost a decade’s worth of work transforming an also-ran into one of the best clubs in the world.

Less than six months later, Spurs are 14th in the Premier League table with just 14 points from 12 games. They’re already 20 points adrift of first place and 11 points out of the Champions League place they’ve come to expect as a minimum standard of performance. And Pochettino, somewhat shockingly, considering the heights he lifted the club to in more than five and a half years in charge, is out of a job. His firing, announced Tuesday, is an audacious bet that Pochettino’s high-water mark is not the same as the club’s, and that a different manager could wring even better results. All from a club that was, until a few years ago, neither athletically nor institutionally capable of mounting the kind of title challenge that would render Pochettino’s performance to start this season as a disappointment.

This bet is all the more audacious, and the reasons for it made much clearer, by reports that José Mourinho is the favorite to succeed Pochettino. Mourinho is not a builder, and hasn’t been for years. The former Real Madrid, Chelsea, and Manchester United boss is a blunt instrument who burns brightly and burns out quickly. Spurs are trying to strike while the iron is hot, but they run the risk that Mourinho melts the iron.

Pochettino never won a trophy with Spurs, but even despite the high expectations of recent seasons, they’re still the kind of club where he will go down as the most successful and important manager in decades. Tottenham’s only trophy of the 21st century is the 2008 League Cup, which hardly earned the manager who won it—Juande Ramos, and admit it, you had to look it up too—enduring plaudits. Ramos, too, was cashiered after a disastrous start to the following season.

What Pochettino did accomplish, however, will have a much greater and more enduring impact than any trophy. The decade after Ramos’s firing was one of great growth for the club, as under managers Harry Redknapp, André Villas-Boas, and Tim Sherwood, Spurs rose from a midtable club to solid upper-middle-class status, capable of qualifying for European competition routinely and even qualifying for the Champions League once in 2010-11. They brought through world-class players like Gareth Bale and Luka Modric, even if they were eventually snapped up by Real Madrid.

It was under Pochettino, who took over the club in May 2014, that Spurs broke through as a genuine contender for domestic and European titles. Pochettino had earned the Spurs job on the heels of a successful 18-month spell at Southampton, in which he brought the Saints up from feeder club status to one of the 10 best clubs in England, and did so while playing an exciting brand of soccer that made his players enticing commodities for the biggest clubs in the country.

In North London, Pochettino performed much the same trick. His Spurs built one of Europe’s great defenses behind Belgian center backs Jan Vertonghen and Toby Alderweireld, and turned young attackers Harry Kane, Christian Eriksen, and Dele Alli into a world-class strike force. Pochettino qualified for the Champions League for the first time with a third-place finish in the chaotic 2015-16 season, matching Tottenham’s best league finish in 26 years. The following year his team finished with 86 points, a club record for a 38-game season, and took second place in the table, their highest finish since 1963. That year also marked an important symbolic victory, as Spurs finished above local rivals Arsenal for the first time in 22 years.

Unlike his predecessors, Pochettino was able to keep the core of his team together; he lost the occasional star to predation by richer clubs—right back Kyle Walker to Manchester City is one example—but consistently reinforced from within, and key players like Kane and Alderweireld remained in the fold. By the time the 2018 World Cup rolled around, the revamped England squad featured five Pochettino-trained Spurs players, plus Walker, on its run to the semifinal. Like Spurs, England played a fast-moving, counterattacking style that relied heavily on Kane as a creator and finisher, further reinforcing Pochettino’s standing as an influential thinker in English soccer.

While Pochettino was building Spurs into a contender, the club was in the process of a billion-dollar campaign to build a new stadium and training ground to place Spurs’ facilities among the very best in the world. Meanwhile, Chelsea continued to engage in its traditional cycle of dizzying ambition followed by hilarious self-sabotage, and Arsenal muddled through the latter days of Arsène Wenger’s tenure, followed by … whatever the hell is going on under Unai Emery. Until 2017, Spurs’ status as the third-best club in London was written in stone, but by mid-2019 they were the best club in the city and by extension one of the best in Europe, with facilities and infrastructure to match.

The past few months have shown the limitations of Tottenham’s program. Ever since the Premier League’s Top Four turned into a Top Six, Spurs have been the lowest-spending club among the EPL’s elite, a fact that has hung over Pochettino’s tenure like the executioner’s ax. Spurs signed Lucas Moura on January 31, 2018, and didn’t sign another new player until July 1, 2019, in the process becoming the first Premier League club ever to go an entire transfer window without bringing in reinforcements of any kind. In the process, Pochettino’s most reliable players either started to age out of their primes or seek greener pastures and higher wages. Eriksen in particular has gone from the club’s creative linchpin to undertaking a kind of sit-down strike after expressing his desire to leave the club during the summer. Even after taking on reinforcements like Tanguy Ndombèlè, Giovani Lo Celso, and Ryan Sessegnon this summer, Tottenham hasn’t been able to turn over the roster as gradually and consistently as is necessary for a club with title aspirations and a Europa League wage bill.

Furthermore, it seems that during the past year, Pochettino’s message has simply gotten stale, which can happen at any team in any sport, when the manager, executives, and star players stay together as long as Tottenham’s have. Sometimes a coach’s message and methods wear out, or sometimes a partnership reaches its natural limit.

Pochettino’s credentials as a program builder, first at Southampton and then at Spurs, are unimpeachable, but now that the program is built, Spurs chairman Daniel Levy is looking for a new leader to guide the club to its first silverware in a decade. The big question before the team now is whether severing ties with Pochettino is a necessary step to avoid the collapse of the contender he spent five years building, or if such a collapse is now unavoidable. Tottenham’s new manager will face dizzyingly high stakes. Not only do Spurs need to continue winning for the sake of prestige, but their financial growth is dependent on media exposure and prize money from the Champions League. Even a one-season interruption in European money flow could hobble the club competitively for years to come.

If this is merely a watershed moment and not the beginning of a fall after a crest, Mourinho—if he is indeed the choice—is a risky choice. One doesn’t have to look that far into Tottenham’s past, to Ramos and Villas-Boas, to find coaches who arrived at Spurs shortly after their managerial peaks, achieved little while in North London, and achieved next to nothing after leaving.

Mourinho alienated players, fans, and ownership alike in his last three jobs, all while burning through resources the likes of which even a newly rich Tottenham could only dream of calling to bear. And if Pochettino’s lost the dressing room, it doesn’t make much sense to bring in the guy whose Manchester United tenure was defined by a series of bizarre and petty feuds with players—stars and youngsters alike.

On the other hand, Spurs might rest at a perfect sweet spot for Mourinho, who always thrived as an outsider but struggled at the helm of clubs with established traditions as national powers. Pochettino managed to establish Spurs as a Premier League and Champions League contender without ever cementing their status with a trophy. If Mourinho is merely in need of the right situation to rediscover his Champions League–winning mojo, this could be the perfect fit. But if he’s just past his best, he could make an already deteriorating situation much worse, leaving Spurs without any of the foundational pieces that turned them into a continental giant, and with a huge, shiny new stadium in which to display the wreckage.