Well they invested a lot of money with Kinect 2.0.
If kinect is not bundled with Xone,it will not sell as much as they projected.(and invested for)
Plus,their Titanfall moneyhat+marketing+free bundle must have cost a lot for MS.
Plus²,the console by itself is not selling like they wished.
So 1 billion loss for Xbox division actually make sense.
On the other hand,it's michael pacter so MS probably earned 1 billion dolars. ;)