Barcelona were by far the strongest team in Europe from 2005 till 2011, they were almost invincible at some stages and the numbers speak for themselves, I mean if three Champions League trophies, four Liga, two Copa del Rey, five Spanish super cup, two European super cup and two Fifa club world cup aren't enough to prove my point, then what is!
What happened in the last couple of years? although they won the Copa del Rey last year and the domestic competition this year, they lacked the competitive spirit at some key matches where they were thrashed in the Champions League against Bayern and also lost 1-3 to Real Madrid in the cup semis at the Camp Nou.
The problem isn't with the tiki-taka, it is still one of the best plans to adopt in recent football, it just needs some polish to restore its magic, and in football polish means new blood, new players that are hungry for titles and at the same time are world class players that can bring these titles.
With the departure of Victor Valdes is on the brink, Barca must find a replacement that is up to big games, and some of the names that are being rumored to join the club are: Valencia keeper Vicente Guaita, Internazionale's Samir Handanović, Liverpool's Reina and Borussia Mönchengladbach's ter Stegen, where I think Guaita is the best replacement for Valdes due to his very fast reflexes, and the fact that he is the youngest among the three (26 years old).
Next is the defense line, Barca's weakest lines, here we should stress on the fact that in Transfer window 1+1 doesn't equal 2, which means that if you buy two class B defenders won't make the same effect as buying one class A defender that can lead the defensive line along with Gerard Pique whom I am sure by playing next to a player like Mats Hummels or Thiago Silva will be back to his best.
In the midfield (the defensive part), Sergio Busquets is one of the best in the world, he knows how his team play, he's been there for a long time and he is still young, but in some games Barca will need two defensive midfielders to own the midfield. So either the coach dedicate Song and Mascherano to this role permanently or he should bring another player like Malaga's Ignacio Camacho, Dortmund's Ilkay Gundogan or Benfica's Nemanja Matic.
As for the center midfield, Xavi is an amazing midfielder, he has the best passing accuracy in the world and maybe in history, but he is not getting any younger and with Cesc not able to fill his shoes completely, the team should start searching for some talents that can lead the field, this role specifically should be played by someone who has the vision and some deadly shots from outside the box. The likes of Marco Verratti (PSG), Bastian Schweinsteiger (Bayern), Ever Banega (Valencia) and Marco Reus (Dortmund) can fit this position perfectly.
Inside the box, Barcelona needs someone who takes the ball and look nowhere but on the opponent's net, they have many players that can visualize the whole field and they definitely do not want to add to the list, that's why I think a player like Edinson Cavani (Napoli), Robert Lewandowski (Dortmund) and Sergio Aguero (Manchester City) will be more effective that Neymar for the Blaugrana.
The season is almost over and the summer transfer window will open soon, I think this year will be a very exciting year in terms of transfers for Barcelona and the other big names, and many surprises will happen, all what we can do now is sit and watch.