It's a disc with some of MJ's greatest hits. Exactly what doesn't make sense about it?
The concept of the album is Past, Present and Future, as you've already been told. Obviously you can't apply the
'Future' concept (unless it's pre-release, in which case the album is technically 'Future'
), but my guess is that because of 'Book 1', there was meant to be more additions of this, so that's what Future could be referring to.
The
'Past' is Disc 1, and obviously refers to his past and as such are a collection of some of his Greatest Hits.
'Present' is Disc 2, and is obviously the material that was released at what was then, the present.
So, because the concept of the album is to include the Past and Present in one package, by releasing Disc 2/'Present' as it's standalone disc, it 'pulls apart' the concept of the album in the first place. I guess you could apply that to Disc 1 too...