Group A and B teams seem extremely unbalanced atm. Hopefully Season 2 will spark new interest from good players.
When we were creating the tiers, I was aiming for all top 7 tiers to be bought by Group A clubs(not counting late sign ups). Apart from 4-6 players, most got bought by A and it seems pretty balanced. A few players from the lower tiers got bought, but it may be due to the league placing them in incorrect tiers.
I would expect all the top tier players in B to be bought by Group A clubs once the transfer window reopens (rules are being formulated, but just like the real world, it would be hard for a B club to hold on to their assets when a richer club comes calling). Over time you want all the top players in A, the mid level tiers floating between A and B, and the lower level tiers in B. As players improve, they will get bought by better clubs.