Money talks and in this month's case, X1 had far more deals that decreased its base cost for the consumer. Let's look at a few examples:
PS4 with destiny bundle: $449.99
Destiny - $59.99
PS4 - $390
X1 with Madden '15 and Destiny free: $399.99
Destiny - $59.99
Madden '15 - $59.99
X1 - $280
X1 with free game and $50 GC: $399.99
free game: $59.99
$50 GC
X1 - $290
X1 with 2 free games, Kinect and 12 months Live - $499.99
free game: $59.99
free game: $59.99
12 months live - I'll make it cheaper than normal $40
X1 with Kinect - $340
So it's actually not hard to see why Pachter and many others believe MS has a good chance of winning September NPD. Essentially a $100 differential in terms of value you're getting for the price.