The simple fact is that Koeman doesn't fancy him. We've all heard the stories (from the England camp for example) of him being a bit of a dope that can't understand instructions and who acts on instinct. If this is true, Koeman will have well picked up on it and prefers a player that can take instructions and work to a plan - someone like Davy Klaasen, who has a sharp footballing brain and technique - exactly what youl would expect coming through the youth system at Ajax - and that's fine in my eyes. As long as we win games I'm good with that.
I don't hope he breaks a log or anything, but my instinct here is that he will be more like a Rodwell or Jeffers rather than a Rooney.