There will be massive swings during your placement matches. That's part of how the Elo system works. You go through a "probation" period (in chess it's usually around 20 games) where it uses a different formula with bigger swings to take you more quickly to your appropriate position. After your "probation" is over, and you are placed generally where you belong, the Elo points gained or lost will be less volatile after each match.
The big problem that I see now is that some inactive players have extremely high Elo's that are untouchable. That makes the ladder stagnant and no fun. Relic needs to reset and introduce seasons, or introduce some form of ladder decay. Right now the ladders count games from the beta, and show players at the top that haven't played in months... that's no good.
This. It also makes us active players less incentive to play. Game is currently unbalanced, people who dont play stay at really high rank..