When Pep Guardiola decided to leave Barcelona in 2012, Alex Ferguson was not the only one left confused by the Catalan's departure from what appeared a perfect set up; "Why would he decide to leave? ... If I were Pep, leaving would have been the most difficult decision to make."
Having created a Barcelona side so firmly rooted in his own understanding of how football ought to be played, Guardiola had managed to marry this fastidious approach with outstanding success; that he never won any trophy just the once is a measure of this.
With an established core supplemented by more than capable moving parts, Ferguson had little doubt that Real Madrid's outstanding continental records of the 1950s were well within Barcelona's reach under Guardiola.
From creator to facilitator, the general mood surrounding the departure of Zinedine Zidane this afternoon has scarcely touched on any feeling of what more there was to achieve. In one regard, leading Real Madrid to three Champions League successes in two and a half seasons may well be read as a benchmark that quite simply couldn't be improved upon.
Although Zidane himself lamented the club's domestic form this season in his parting comments, he did lead the side to La Liga success last season, and, after the club's poor domestic form lead to Rafa Benitez's departure during the 2015/16 season, it was Zidane who led them to within a point of the winners Barcelona in the end.
Yet, to whatever degree Zidane will be credited and remembered for his role in Real's modern domination of European club football, he, unlike Guardiola, will always be seen as a player first, and manager second.
A surprising departure so soon after the club claimed their third Champions League win in succession, one cannot escape the feeling that this exit is exactly what Zinedine Zidane deserved.
Describing the Frenchman in his 2016 book, Football, Jean-Philippe Toussaint recognised an unusual recurrence in the playing-career of Zinedine Zidane; "He has never been able to bring himself to finish."
Looking primarily at his wildly successful international career, Toussaint highlighted the repetitious nature of Zidane's 'unfinishedness', reaching its climax as it did in the 2006 World Cup final:
Zidane is familiar with stage exits (against Greece), or bad endings (against South Korea). It has never been possible for him to bring his career to an end, and even, and particularly, to go out in a blaze of glory, because going out in a blaze of glory is still ending the legend: to brandish the World Cup is to accept death, while a bad ending leaves perspectives open, unknown and alive.
Incapable, or unwilling, Zidane's outlandish exit in 2006 leaves one torn.
Head-butting Italy's Marco Materazzi in the chest in extra-time, how do we rationalise such an act from a footballer who so supremely demonstrated his control in other avenues?
Yes, like his national compatriot Eric Cantona, Zidane was known for his short-temper and impetuous acts of hostility. But, in a World Cup final? Moments away, perhaps, from achieving the incredible feat of winning two winners medals, eight years apart; was, as Toussaint suggested, blazing out in such glory tantamount to accepting death, ending the legend once and for all?
Speculation abounds that had Zidane failed to lead Real Madrid beyond Liverpool in last weekend's Champions League final, he may well have departed the role anyway, in slightly different circumstances.
In spite of his success up to this point, it had been heavily rumoured that Real's poor domestic form would cost him his job before ever reaching this point.
So, on such uncertain ground, has Zidane adapted and vouched for the "blaze of glory" exit? Or, is this latest move yet another example of his desire to remain wholly in control of his own narrative?
Few can now name the managers in charge of Bayern Munich, Ajax, or indeed Real Madrid, as those clubs achieved their three or more European titles in a row. Perhaps merely a consequence of time, yet, we have not forgotten Franz Beckenbauer, Johann Cruyff or Alfredo Di Stefano.
Maybe Zidane has dispatched the characteristics Toussaint identified, and opted for the heroic exit. However, with Madrid's white tassels still hanging off the jugged ears of the Champions League trophy, the Frenchman has once again managed to take us all by surprise.
We are never likely to forget the manager of this great team.