I think this is spot on. He can only play in the AM role for us regularly, and it’s a pity because a) Rooney will always play b) Martial is by far our most threatening player so he shall always play c) Mata is our best player on the right wing and d) Memphis is very highly rated by van Gaal, hence he got so much time to find his feet (I disagree with this tactic btw).
I really think Herrera is extremely unlucky. In a normal, healthy team I suppose Rooney would find himself on the bench, so would Memphis- replaced by Martial and Young respectively. I think it would make much better team with Herrera behind the front trio than what we’ve been playing recently. I guess that until Young/Memphis comes back, Herrera will get his chance. But unfortunately I wouldn’t bet on him staying in the team longer, he’s the victim of circumstances.
I don't believe it's all doom and gloom for Herrera. After all, he did get a special mention for his performance at Goodison from LvG which is something that doesn't happen very often. As for the personnel i think Martial, with his performance on the left wing, kind of "opened up" a spot for the #10 position. He really made Coleman look like a championship player and we have to take into consideration that a natural dribbler, more so someone who can ridicule the opposition FB on his strong foot is something that we desperately need in the wide areas. If that's the case, Rooney will be pushed up front.
Tactically wise, i think Herrera will always be a candidate for the starting xi as long as LvG continues to set his team to press and defend a bit deeper than usual. After the fiasco at the Emirates and with the fear that Lukaku would beat our defenders to the ball and invite runs from the players around him LvG decided to go for a more cautious approach off the ball. When you give the opponent a few yards on the pitch
and do your defending right, then you can be more direct on the ball cause there are more spaces to exploit. Under these circumstances Herrera can thrive.
That special mention from the manager wasn't a coincidence. The assist came from what LvG describes as "half zones" in between the opposition lines and it's where he believes that the best assists/through balls can come from because the player on the ball can see all the off the ball movement and make the right decision. Mata starts from the right and has absolute freedom to search for this kind of passes. The goal was an excellent run towards the far post, a "classic" second striker move.
Add his nearly perfect passing percentage and the fact the he did much better at protecting possession in the attacking half and you have the whole picture. The only issue here is that probably LvG doesn't expect that these spaces behind the defense will always be there. I doubt he'll ever choose to defend even deeper and go for a more gung ho style as he desires/demands control of the tempo. In that case the spaces have to be found in between the lines and it's pretty obvious why he'd prefer a Bergkamp-Litmanen-Mueller type of player there. I like to think that the manager is on the verge of accepting the fact that Rooney, with his current woeful first touch and his inability to play with his back to goal, isn't suitable for that role. Instead, he still has pace to look for runs off the shoulders of the defenders. So, the different tactics we use whenever we have to deal with a very physical forward (Goodison, St Mary's, Liverpool game) could be used more often and with Martial showing ability on the wings, Herrera will get more playing time.