On a club level, it can be explained by the mass injection of Sugar Daddy cash into clubs, enabling them to buy a quality squad which dominates any club which isn't owned by a Sugar Daddy. The fact that it's happening on an international level at this World Cup is baffling.
Perhaps it's something to do with the particular circumstances of each team: Spain were on the decline and under intense media pressure to perform, as they reported to be falling giants. Also, to use a cliché, they perhaps did not want it as badly as Holland, having already won three trophies in the last six years. Brazil's players, on the other hand, have a huge burden of expectation on their shoulders, so when you couple that with the loss of Thiago Silva and Neymar, it becomes very hard to bear.