I wish I hadn't pointed out that G-Rating wasn't necessarily appropriate....
If you reject G-Rating for picking the whole team, as you should, you cannot pick players on the basis of their G-Rating alone by the same arguments. Similarly for the leagues and GFDT.
I would suggest therefore that there are two options available.
1. A new sort of rating system that takes into account the factors you view as relevant.
2. Subjective decision making, perhaps with short-lists made by G-Rating.
Or a mixture of the two.
For instance, a WTA only G-Rating could be calculated, or a G-Rating with greater weight to WTA games (I quite like the latter option, apart from the processing power necessary), to create a shortlist, from which a decision is made, based on looking more specifically at the results in games against stronger players, and looking at league positions, for instance.