In the old days, teams would rise to the top slowly. Each had to wait in line until the teams above them retired. The next-to-top finishers at the Olympics would automatically be pencilled in as the medalists four years thence.
Now, teams seem to have a lot shorter shelf life. Belbin and Agosto give way to Davis and White, and Davis and White in turn are soon to be surpassed by the next wave. Two years ago Domina and Shabulin were all but given the 2010 Olympic gold medal. Now they are being pushed aside by Khokhlova and Novitski.
Also, injuries seem to be playing a much greater role than before. There is no guarantee that Delobel and Schoenfelder, or Belbin and Agosto, or Domnina and Shabulin will even make it to Vancouver.