It's got to be more than they've simply just been 'found out', we knew how to play them back in 2011 but it didn't help us a jot.
They've certainly lost that intensity to hunt the ball when they don't have possession but maybe they're all just knackard from playing so much football over the past 5 years? Whatever the reason I think it's a little early to be writing the obituaries like Redknapp was doing on Sky earlier :/
Its simple, people like to give a new manager instant credit as if an old manager, and the actual players had never even seen a football before the day they took over. Mourinho with Chelsea, they started off with a great defense but were a VERY attacking team under Ranieri, they were very attacking when Mourinho took over, but essentially with every passing month they were a less attacking side, more defensive and found it more difficult to attack. Its a case of Mourinho's methods taking a long time to overwrite the previous regime. The mix of the previous attacking side + a focus on defense made them a great team, but after 2 years they just started to look dire, and boring, and overly defensive.
I think its the same here, when Pep took over you had a hugely attacking side, with pace, who played very varied football, and started to use possession to control games but were still very varied. After 3 years they became a very single minded Tika style team, Pep's methods were ingrained and the old team he took over were essentially gone. THey are now a pretty boring, single minded team which is far far less good than it was, very limited and essentially running out of ideas.
The difference between how Barca played in the first year under Pep and the last year, and how they play now is HUGE< absolutely HUGE.
Defensively, Puyol, in form Puyol destroyed strikers, dominated entire attacks, he was a freaking beast. Even when he plays injuries have pretty much meant he's rarely in form or match fit, and he's barely playing. Pique with Puyol beside him and Pique on his own, also night and day.
Alba, massively massively over rated, Abidal and Maxwell are hugely better defensively and have been huge losses(for different reasons), if Abidal can make a significant contribution next year, well he can play CB so they could be improved, but frankly they should be buying a replacement for Pique and playing whoever that is alongside Abidal.