Best way to undersand Valverde's tactics is to make the difference between proactive, and reactive. A defense will clearly block your central players the most. DM, CM, AM + Messi in our case, the central backbone of Barcelona. This will mean that the fullbacks will be left mostly free to receive from the CBs, because the defending team doesn't see them as major risks. You don't block fullbacks initially, because if you do it means you leave central players more free and you certainly don't want that. Fullbacks are usually one-footed players, and they don't see the game in 360 degrees, so once the ball gets to them the areas you have to block are more reduced, than in the case of a central playmaker, who can usually pass with both feet and has a complete view of the field. The question now is what do you do as a manager when an opponent is blocking you the most important creative players and leaving your fullbacks free to receive very wide.
This is basically where great managers are different than your average Valverde type manager. They will simply not accept this situation, they will not accept a defending team to dictate how their team will attack. They will look for ways to unlock the central players and continue to build centrally. Instead, the mediocre managers will accept the offered route with humbleness, even if they know that the defending teams offer that route only because it is the easiest to defend and the least qualitative way of building attacks. Valverde is a conservative, standard manager whose ideas are set in the 90's style wise. The great managers are more modern, and simply are more advanced in terms of way to generate space. To make a comparison, Pep and Klopp and other top managers are like blu-ray disks and Valverde is a floppy drive. A floppy drive can still store data. It works. It's just outdated and ineffective past a certain level.
This is the first instance where a Pep, or a Klopp, is completely different than a Valverde. It starts with the simple idea of imposing your way of playing. They will not take what the opponent is giving. They will force the opponent to give them what they want.