He scored a great goal. That's the thing. Khedira saves his skin because he makes good runs forward and scores often but given his sluggishness he's defensively a non-entity. Matuidi can score too, Can looks like a threat going forward also. But they both, as far as I can see, are dynamic enough to cover defensively and keep the ball at the feet of our players.
Khedira's goals have been his alibi but shouldn't be enough to save his spot. Matuidi has always allowed us to control midfields, even if he's a tad sloppy. He applies pressure, makes oppositions mids nervous. That's what's needed in our midfield. And just because he's a black ball winner doesn't make him Sissoko. His skills are still far superior, Momo's assist to Krasic being a notable flukey exception.