I have figured how this whole rating system works. And In Short Answer, The moral of it has to do with Tech. and Design.
Now for the longer answer, Its based on its expectation. The Game is somewhat programmed that If for example, the new Game has a newer T & D than its previous T & D, supposed 1/2 of it, the rating would go higher, vise versa.
The game does give you many options in helping you maintain that balance, however.
Fill free to correct me @PatrickKlug , after all , It is based on my assumption.