It would most likely have been 4 out of 9 games if Rooney didn't get that red card, though... Kagawa was also third in shirt sales for quite a while. Shirt sales will not keep a player around.
I can believe that Mata doesn't want to leave and that Van Gaal wants to keep him. Having a player like Mata as a backup, is a luxury few other teams can enjoy. As for Mata, I don't think he's ready to give up and go to a weaker club just to get more playtime. Kagawa was lucky in the sense that he had the opportunity to go to a better team and be guaranteed to start in his favored position. Mata doesn't have the same luxury. Chelsea wont take him back now.