Forming the teams according to some overall ranking has a non-political
overtone that I very much like.  As soon as you bring in head-to-head,
then you've opened yourself up to all sorts of bickerings and political
solutions that may have no basis in fairness.
 
I missed the description of what will happen in following years but, as
one poster suggested, rotating teams through the divisions makes sense
in the long run.  Of course, there is no such thing as scheduling for
the long run.  :-(