(A series wherein I propose the sweeping changes necessary to salvage these once-beloved characters)
First thing's first: The explanation ain't half as important as the results. I'm afraid another reboot's in order - with the following caveats:
1. Some stuff should directly follow continuity from before the New 52 (i.e., Teen Titans picking up after the events of The Titans vol. 1 #25).
2. Some stuff should integrate all the aspects of the character(s) that have worked best up until this point.
Beyond that, I'm just going to be throwing out suggestions to see what works. No particular order - and frequently brief, so as not to run out of material. For instance...
Top 3 Explanations For The (Aforementioned) Reboot:
1. No explanation given - nor is one necessary.
2. The New 52 was really just Earth-52 all the time!
- or (my personal favorite) -
3. The New 52 was a mass hallucination created by the Black Mercies!