It is often said the Premier League has transformed English football.
And so it did. But this has been a revolution of unusual stability.
For years the landscape of the division looked similar. Power was concentrated in the hands of a select few, each with his own stronghold.
It would be an exaggeration to say nothing changed, but outsiders looked on, marvelling at the continuity.
Then came the summer of change.
At a stroke, everything appears different.
Out with the old have gone the assumptions that underpinned the division for years. In with the new has come the promise of excitement.
An era of uncertainty has begun.
To some, Manchester United, the defending champions, are the likeliest to claim the title.
To others, Manchester City, the biggest summer spenders, are.
Perhaps, actually, it is Chelsea, who now possess the manager with the best CV in England.
For so long, that was Sir Alex Ferguson, but the post-Ferguson world looks very different.
It was always going to.
Having moulded the past, Ferguson is shaping the future. David Moyes was his hand-picked successor, and Jose Mourinho the man who was thus allowed to join a rival.
While Arsene Wenger inherits Ferguson's mantle by becoming the country's longest-serving manager, Mourinho - including Uefa Champions League titles for Porto and Inter Milan - is the most decorated and, perhaps, the most influential.
For long, Ferguson was "The Godfather". Now, with three of Mourinho's protégés - Andre Villas-Boas, Brendan Rodgers and Steve Clarke - serving as managers in their own right, the enfant terrible could be the eminence grise.
It is a remarkable development, but not the only one.
Since the foundation of the Football League in 1888 the top three clubs had never changed managers in the same summer.
They have now, with Ferguson, Roberto Mancini and Rafa Benitez replaced by Moyes, Manuel Pellegrini and Mourinho, respectively.
While Ferguson could merely burnish his legend, now everyone has something to prove.
Even Mourinho, whose status among the greats would have been secured had he won the Champions League with Real Madrid, has unfinished business.
Others have to show they are not allergic to silverware. Moyes's 11 years at Everton did not yield a trophy nor - with the exception of the Intertoto Cup - did Pellegrini's nine seasons in Spain.
Wenger's personal drought at Arsenal famously dates to 2005. The managers of the Manchester clubs and Chelsea could not afford as long a wait.
And their fortunes are linked. Perhaps the most intriguing relationship is between Moyes and Mourinho.
The Scot initially appeared to welcome the prospect of verbal warfare, insisting "bring it on" before praising the Portuguese in some placatory comments.
Yet it is not merely the suspicion that the job Mourinho coveted now belongs to Moyes that adds intrigue, as Chelsea's public pursuit of Wayne Rooney adds another dimension to the rivalry.
The Portuguese is canny enough to recognise that buying the forward would serve two purposes, strengthening his side - who desperately require a striker better than Fernando Torres - and damaging one of the other contenders.
As such, it has the potential to be still more pivotal than Ferguson's recruitment of Robin van Persie: much as his other suitor, Mancini, lamented the one who got away, City were not actually weakened by the Dutchman's move to Old Trafford and Arsenal were not actually title contenders.
Yet the reality for Moyes and Mourinho alike is that they are yet to make a defining signing.
The Scot is discovering that spending a sizeable budget is harder than he imagined when dealing with more meagre funds at Everton.
The Portuguese has seen Paris Saint-Germain and Monaco behave in the way Chelsea did when he first joined, trumping more prestigious clubs with huge offers.
The modern-day Mourinho and Chelsea have been more understated now, bringing in Andre Schurrle, Marco van Ginkel and Mark Schwarzer. Each is still looking for his superstar recruit.
And so the mischievous Mourinho, not quite settling into the role of the elder statesman, has applied pressure on Pellegrini by saying City's spending makes them favourites.
The Chilean has been the exception, doing his business swiftly, comparatively quietly and decisively. Enter Fernandinho, Jesus Navas, Alvaro Negredo and Stevan Jovetic for a combined cost of around £90 million (Dh511.3m).
It represents the opposite of last summer, when, as Mancini complained long and loud, City's signings arrived late and were invariably ineffective.
Yet Pellegrini has been appointed to be the antithesis of Mancini - more of a man-manager and conciliator, less a controversialist - just as part of Mourinho's appeal is that he is not Benitez.
The interim manager was hated by a section of the Chelsea support and merely tolerated by others.
Mourinho is loved by them all.
For Pellegrini, besides securing victories on the pitch, his initial aim has to be winning over the supporters who were loyal to Mancini.
Earning personal popularity should be a mutual objective in Manchester.
While some United fans were underwhelmed by the arrival of a manager whose personal trophy cabinet contains the English third-division title, won with Preston in 2000, the Community Shield and nothing else, Moyes is helped by having a high-profile cheerleader.
As he addressed the Old Trafford crowd for the final time, Ferguson said: "I would like to remind you that when we had bad times here, the club stood by me, all my staff stood by me and the players stood by me. Your job now is to stand by our new manager."
Steadfast backing may be required. The reality is that United have been handed a tough start to the season.
There are early chances for literal and metaphorical point-scoring between the three newcomers.
Moyes's first competitive home game is against Mourinho's Chelsea. Less than a month later, he travels across Manchester for his first derby against Pellegrini.
The spectre of Ferguson loomed large over City for decades, but those days are gone.
An has era ended.
Now there is a chance for another manager to define his time.
And the three main candidates are Jose Mourinho, David Moyes and Manuel Pellegrini.