Where are you getting your stats? I think what they are saying is Ghost is the best selling game on next gen and they combine both the XBONE and the PS4.
Infamous sold a total of 1,837,473 copies total
Titanfall sold at total of 1,633,123 copies total
Ghost sold a total of 2,164,283 copies total of the PS4 according to VGCharts
http://www.vgchartz.com/weekly/41756/Global/%C2'>
I don't pay for pro so I don't know what it is for the XBONE but if you combine the two I wouldn't be surprised if it had the highest number of sales "For the Next Generation Consoles".
It is marketing and Activition is doing what it can to put a spin on the relatively mediocre sales for their main franchises to their share holders. If you look at their stock reports WoW and CoD sales a down (a lot, but not as bad as forcasted) so they want to positive spin on things. The results are not surprising to me. People who rushed to buy the consoles are the hard core gamers and if you look here the vast majority of people playing on next gen are all playing BF4 or Cod.