Dying Light sold 5M+ on PS4, Xbox One and PC as of the 13th August 2015.
VGChartz has all 3 versions at 1.6M. Of course there are digital sales, but I don't think that they are so huge!
Don't forget it was digital only in Europe for the first month so digital sales are likely to be higher than usual.
Bet Shiken that COD would outsell Battlefield in 2018. http://gamrconnect.vgchartz.com/post.php?id=8749702