Pep Guardiola got out while the getting was good.
Few could have predicted the ease with which Bayern Munich tore apart Barcelona as the Bavarians won, 4-0. The Catalans were outclassed in a way rarely seen during the club's dominance over the past few seasons.
It's easy to forget Barcelona is 13 points up on Real Madrid for the La Liga title, and that lead was maintained while Tito Vilanova was on medical leave. You would never have guessed it after the first leg of the Champions League semifinal was over.
With Guardiola, Barca's previous manager, destined for Munich, Jupp Heynckes made sure to let everyone know he's the manager of Bayern for the time being.
Although this result surprised many, there were plenty of warning signs for Barcelona, and issues that need to be dealt with as the specter of the German giants is sure to loom large in the second leg and surely next season as well.
No Plan B
Many brought up this point when Barca was bounced by Chelsea in the semifinals last season. The Blues bunkered in, allowing their opponents to run at them without getting too many great chances on goal.
Chelsea rode their luck quite a bit, but it still illustrated a major problem for Barcelona: if the club can't break down its opponents with its tiki-taka football, it doesn't stand a chance.
Bayern didn't have to rely on ultra-defensive tactics like Chelsea did. Like Chelsea, Bayern chose to sit back and defend, while pressing at the right times. Unlike the Blues, the German club was confident going forward and didn't worry as much about the Barca counter.
Barca's possession was ultimately meaningless because it could do nothing with the ball. Despite scoring four goals, Bayern only had roughly 34 percent possession.
Bayern closed off any and all attacking options for the Spanish club. The Catalans couldn't switch the game up and try long balls forward because it's not in their makeup, and they lack the centre-forward capable of holding the ball up.
Although some may consider him a failure with the club, Zlatan Ibrahimovic did manage to bring a different dimension to Barcelona during his time there.
It's wonderful to watch Barcelona when the club is at its attacking best, and clearly the style has been effective. But there are times when that doesn't work, and if Barcelona wants to reach the summit of European football again, it will need to adapt its game accordingly.
Lack of Height
During most pre-match hype, many of the talking points talked about as game-changers often turn out to mean nothing at all. Barcelona's lack of height was considered to be a major problem that Bayern would exploit, and exploit it the Bavarians did.
It almost became comical just how much Bayern dominated in the air.
The first goal came about as Arjen Robben's cross was headed by Dante to Thomas Muller. Then, in the second half, Muller headed a Robben corner across to Mario Gomez, who finished for Bayern's second goal.
Aside from Gerard Pique and Sergio Busquets, Barca lacked the kind of size on set pieces that could help to negate the height Bayern had.
It goes along with with the first problem. Barcelona has stockpiled smaller, compact players who are talented on the ball and can go forward very well. That's come at the expense of bringing in bigger, more physical players who could have a role to play in certain situations.
Over-reliance on Lionel Messi
If you're going to rely on one single player, it might as well be the best player of his generation. But even Lionel Messi couldn't save Barcelona on Tuesday.
Javi Martinez and Bastian Schweinsteiger did extremely well to cut off his supply in midfield. Messi had to increasingly drop back to receive the ball. The Argentinian forward is capable of incredible runs through defenses, but you don't want to see him coming into the midfield if you're Barcelona.
It didn't help that Messi looked unfit. There was some question as to whether he would be ready for the match, and he ultimately received the go-ahead from Barcelona's medical staff. Considering how poor he was, it's not unfair to call into question the decision to play him.
As the season has gone on, Barcelona has become increasingly reliant on its star goalscorer. Sooner or later, though, Messi deserves a rest.
If Barca really trusted the players behind Messi to have enough to get a result against Bayern, the club wouldn't have played him. It's telling that it felt a half-fit Messi was the best possible move.