Yeah, movement.
Kagawa's coach and mentor in Japan clearly stated that Kagawa's biggest strength wasn't his techinique or creativity, but his intense, constant and clever off-the-ball movement. Kagawa got the best BEEP-test scores sice Beckham. Hardly a coinscidence.
You can criticize Kagawa for a lot of things. Lack of confidence, lack of aggression, lack of strength, too unselfish, and too unwilling to take on players etc. This is all valid critique. But there are 3 things that Kagawa excels at to a degree that's so high that it would be preposterous to criticise it, seeing as he's right up there with the very best: off-the-ball movement, technique, and football intelligence. In these aspects, he's among the best in the league. And if we change our style to better accomodate these skillsets, then Kagawa will obviously play better. And that is why I'm so happy we signed Mata. Like some other people have posted, it truly is a blessing in disguise.