He'd operate much better in a MF3, Van Gaal has practically spayed all of the mobile defensive ability that he had. His pressing is completely different now than at Bilbao. Much less to do with chasing the ball and more about reading the play and I don't think that is his strength. He'd be much better off with the time and space to close down the ball without the responsibility of holding his zone. Iturraspe, De Marcos, Gurpegui and Martinez were much better foils for him in the three at Bilbao.
This squad at the moment really doesn't have a suitable three combination at all. Especially with Schweinsteiger/Carrick doing a timeshare when they aren't injured. It is a bit of a mess which is why Van Gaal has completely changed Herrera's game. Which imo is for the worse and away from what would be a strength domestically in England but that is my opinion.