Mata's performances for Man Utd could see him recalled to the Spanish side if Del Bosque still thinks he needs a false #9.
Its interesting that Van Gaal has his forwards split and go either side of Mata when we don't have the ball, effectively Mata plays centre forward when we defend. When we have the ball this changes and Mata drops off, bolstering midfield and allowing us to gain a numerical advantage in the middle third. If you count pre-season, more than once the role Mata's playing has had a huge impact. The third goal against QPR was a great example. In the build up to that goal Di Maria, Herrera and Mata are all in the inside left channel, which created the angles that allowed us to move the ball rapidly around QPR and up to Rooney. Of course, Herrera still had to be gifted enough at one touch passing, and quick enough upstairs to go with the play, but the fact he had Di Maria and Mata close made it possible to play the pass and move game Herrera excels at.
What Mata's doing for us is exactly what a false #9 is meant to do. Furthermore, I don't think I have seen any other Spaniard do it quite as well. I always felt Cesc was ill suited to that role and I'm not sold on David Silva acting as the central focal point of Spain's attack either. Silva is less direct and less muscular in his play than Mata, he works better off other players drifting in off the flanks. If given the chance I could see Mata thriving as a false #9 for Spain.