This is not a piece designed to denigrate Barcelona or troll their fans. And obviously their manager's recovery from cancer is taking a noticeable toll on their performances. These are just observations of what appear to be patterns emerging in their play that teams are starting to identify and decode.
The first thing that jumped out at me during the Milan match was Barca's glaring and repetitive reliance on a (admittedly pretty at times) curving ball down the right flank for Dani Alves or Pedro to latch onto. They tried this method of attack time and again and Milan, taking nothing away from their discipline, positioning and work-rate--all of which were phenomenal, seemed exceedingly aware that this would happen, making it easier for Kevin Constant and Philippe Mexes to be in position and close down Pedro and or Alves before they could cross and get the ball into dangerous areas in the box. The predictability of this strategy also allowed Milan to retain their shape and focus in the center of the pitch where Max Ambrosini and Sulley Muntari, in particular were able to press Xavi, negating his ability to control the tempo of the match and facilitate his typically intricate triangular passing combos and precise through balls. Perhaps Milan's success here actually dictated an over-reliance on the arching balls down the right side of the pitch.
With his typical line of supply cut-off, Lionel Messi was forced to drop deep to try and gain possession, which obviously forced him further away from goal where he is so lethal. Michael Cox made an excellent observation in his recap of this match on Zonal Marking, which was that Milan, in a nominal 4-3-3, adopted a "lopsided" approach wherein:
"Boateng stayed deep and narrow on the right of midfield, but Stephan El Shaarawy stayed higher up on the left, ready to break in behind Dani Alves. This afforded Milan the perfect balance between defensive structure and counter-attacking potential."
Perhaps it was simply a coincidence, but I strongly doubt that ZM noticed the effectivness of this approach and Jose Mourinho did not. Which is probably why, as Lucas pointed out, Angel Di Maria played deep, not only helping Alvaro Arbeloa defensively, but allowing Cristiano to play further up and reek even more havoc than normal. Real Madrid seemed to employ the same formula, a slightly misshapen formation where one attacking midfielder, in this case Di Maria, stays "deep and narrow" while another stays high up the pitch ready to break on the counter.
Khedira and Alonso dominated the midfield on Tuesday evening, again replicating in some fashion what happened at the San Siro, pressing Xavi and forcing Messi to eventually drop deep where he is less effective. The wide problem I had mentioned earlier the regarding the predictable long balls down the right to Alves or Pedro is becoming so well known that teams are apparently conceding this wide play down the right and doing their best to clog, press and close down any outlets through the middle, while stifling Alves and/or Pedro as soon as they receive the ball. Both Milan and Madrid did this effectively. This is also a strategy that played right into Madrid's hands as Fabio Coentrao, in particular, has a unique ability to defend this shopworn Barca tactic extremely well due to his pace and he closed down Pedro multiple times before anything dangerous could manifest.
Are these patterns and formulas that any side can implement? It's too early to say that. But Zonal Marking did make another telling observation regarding exposure to Barcelona's style, writing:
"And how important is experience of playing Barcelona? Barca’s two key defeats this week have come against sides now accustomed to facing them – Milan played them four times last season, Real Madrid six times. After ‘aggregate’ defeats in 2011/12, maybe Allegri and Mourinho have learnt lessons for 2012/13."
Allegri and Mourinho are respected managers with considerable resources at their disposal, but it seems only a matter of time before more and more managers learn from what has occurred over these past few weeks.