Barca won their fifth European Cup in 2015 and the signs of decline have been evident over the past five years since -- but no-one envisaged a fall as great as this.
For Bayern Munich coach Hansi Flick, Friday's remarkable 8-2 hammering of Barcelona must have felt like the most wonderful deja-vu imaginable.
Flick had sat on the bench in Belo Horizonte in 2014 as assistant to Germany head coach Joachim Loew, as Germany handed five-times world champions Brazil their worst ever World Cup defeat with a shocking 7-1 victory.
If that will be remembered as one of the greatest performances by a German team, it will now be run close by what Bayern produced at an empty Estadio da Luz on Friday.
The trauma of "The 7-1" still reverberates through Brazilian football, the sense of embarrassment and anger at the loss, the fierce debates over blame and then search for solutions, continues even six years on.
It is hard to imagine how long it will take Barcelona to get over the impact of "The 8-2" but while the Brazilians had four years to get themselves sorted for the next World Cup, no such breathing space exists for Barca.
Luiz Felipe Scolari resigned as Brazil manager the day after the conclusion of that World Cup and it appears Barcelona coach Quique Setien will leave his post with even greater haste.
If he does, he surely won't be the only one to pay the price for a ragged performance, in which his side appeared to throw in the towel in the latter stages.
"I think that right now it's too soon to be talking about whether I stay at the club or not," Setien said in the immediate aftermath.
"The reality is that it doesn't depend on me. It's worth all of us working out what's important and considering a wide range of things which correspond to a defeat of this importance and which is so painful."
Such an inquest will begin right away in the local press which is unlikely to be sparing in its criticism.
Barca won their fifth European Cup in 2015 and the signs of decline have been evident over the past five years since -- but no-one envisaged a fall as great as this.
The days when Andres Iniesta and Xavi produced the wonderful midfield passing dominance behind the wonders of Lionel Messi and Neymar, allied with Pep Guardiola's tactics left the continent purring at Barcelona's class, feel increasingly distant.
Children across all corners of the world chose to wear the clubs famous blaugrana striped shirts, just to be associated with the wonderful brand of football Barca were producing. But it will be the club's hardcore support in the Catalan city who will be demanding change.
Barcelona have paid the price for the failings in recruitment, bringing in too many players who weren't up to the club's standards.
When they have signed players of undoubted quality, too often they have failed to integrate them into the team.
Nothing highlighted that more than sight of Philippe Coutinho, signed for more than 100 million pounds ($130.84 million) from Liverpool but now loaned out to Bayern, scoring twice in the final minutes against a defence that stood almost motionless.
The 'Barca way' is a team that wins playing attractive, entertaining football and this loss and the manner of the defeat was so far away from that ethos, that it is surely going to take a very painful process to rediscover it.
