Not a soul saw it coming. Not here, at least. And certainly not now. Not in Rome. Not on April 10. But that doesn’t mean it hadn’t been coming.

It had been coming for months, thinly veiled by the La Liga table, and by the brilliance of a transcendent superstar. It had been coming since Neymar lusted for Paris, and perhaps even longer than that. It had been coming. The only shock was when and how it arrived.

Barcelona’s Champions League campaign unraveled over 90 stunning, upending minutes on Tuesday at the Stadio Olimpico. Roma, an afterthought after a clumsy 4-1 loss in Catalonia six days prior, staged one of the greatest comebacks in the competition’s history. Barcelona, owner of the greatest comeback, sunk to the other end of the emotional spectrum.

Last year’s miracle at Camp Nou, though, is a decent place to begin explaining Tuesday’s calamity in Rome. Because the man who catalyzed it wasn’t present this time around. And his absence, while not necessarily illustrative of the difference between the two Barcelona teams, explained why the similarities between the two teams are problematic.

He, Neymar, was a member of the famed front three who spurred Barca on to three years of glory. He also was part of a Blaugrana transformation, from the imposing possession and juego de posición of Pep Guardiola to the rampant and expansive counterattacks of Luis Enrique. He was part of the attacking trident that allowed those counters to flourish; that rendered possession and control less necessary.

But his talent, and that of Lionel Messi and Luis Suarez alongside him, also papered over the cracks. His brilliance that night against PSG saved Barcelona from an alarmingly early exit that it probably deserved.

His personal exit in August seemed to expose those cracks; to reveal the wasteland that was Barca’s 25-28 age bracket, and a squad no longer overflowing with talent.

Curiously, it didn’t. Or at least the cracks didn’t show up in Barcelona’s results. The Catalan giants are seven games away from the first unbeaten season in modern La Liga history. They’re effectively one win away from a domestic double. Ernesto Valverde’s first season had gone better than Enrique’s last; better than expected. Until Tuesday.

On Tuesday, Barca crumbled – just as Neymar’s departure promised.

Ernesto Valverde has furthered the Barcelona transformation, from a dazzling quick-strike attacking unit into, well, not quite an attacking unit. Barca has gone defensive and relatively dull. Valverde has reined in the press. He’s slowed the attack.

The evidence is all over. Barcelona’s passes allowed per defensive action in the opposition half (PPDA), a measure of the intensity of a team’s press, has risen to 7.94 this year, per understat.com, compared to 6.31, 5.66 and 5.56 in the three seasons prior. Its possession percentage, 60.8, is its lowest of the decade, per whoscored.com, despite midfielders suddenly averse to risk-taking.

The priority has been defensive solidity, and the results have been excellent. This time, it has been the system closing up cracks in defense and midfield, rather than a rampant attack obscuring them. Barca has conceded just 16 goals in 31 league matches.

The idea, seemingly, has been to dominate defensively as a unit and going forward as individuals. Andres Iniesta is averaging just 0.07 Expected Assists per 90 minutes, well below his career standard. Ivan Rakitic’s attacking contributions have declined. Barca’s third and fourth best chance creators, after Messi and Suarez, have been its fullbacks. By comparison, over the previous three seasons, the starting fullbacks’ team ranks, on average, were 6.7 and 8.3 (xA per 90 among players with at least 1,000 minutes, via understat.com).

The attack, increasingly, has run exclusively through Messi, and Messi has been good enough against overmatched domestic foes to carry Barcelona to a title. The defense, meanwhile, has been propped up by a breakout campaign from Marc-Andre Ter Stegen, who’s conceded just 16 times on over 26 opponent Expected Goals.

But that is La Liga. The staunch defense was simply unsustainable. The Champions League proved to be a different animal. In the quarterfinal first leg, Barca was bailed out by good fortune. In the second leg, it had no such luck.

In the second leg, it looked uncomfortable in possession, and incapable of winning it back. In defense, its combination of good-but-not-great talent and buttressed scheme unraveled under pressure from an opponent that had the quality to pick it apart. And with Messi marked out of the game, Suarez aging and ineffective, and Neymar gone, the favorites had no Plan B.

Throughout Enrique’s tenure, Barca became reliant on its front three. When that front three became a front two, reliance became over-reliance, and Valverde didn’t have the supporting pieces to truly change. His adjustment was to ask less of his aging, sub-world-class midfielders. And for almost an entire season, the short-term fixes have worked.

But the latest stage of the evolution had been tempting fate. And finally, on a memorable Tuesday night in Rome, the deficiencies compounded one another, and Barca cracked. Its underbelly was exposed to the world. Its failure was shocking – but not exactly inexplicable.

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Henry Bushnell covers global soccer, and occasionally other ball games, for Yahoo Sports. Have a tip? Question? Comment? Email him at henrydbushnell@gmail.com or follow him on Twitter @HenryBushnell.

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