It's interesting that they had his old manager from Dortmund on Football Focus (Klopp, right?), who was saying that we hadn't seen Kagawa's best, partly from injury. The timing of that statement and this game was pretty serendipitous.
One thing worth mentioning, apart from the goals (which are worth man of the match on their own), was that we have been talking about his ability to perform well for a whole 90 minutes, rather than fade away, and his last 2 games came much later in the match than he has normally been performing effectively at. Maybe it was just a matter of fitness, recovering from injury, and adjusting to the style of the league. Or maybe it was just one match. If he can perform near to this fo the rest of the title run-in, he'll have come into form at just the right moment.