The tastes of the directing branch skews indie, arty, and avant-garde, but from talking to voters, it seems as though the Affleck snub came about simply because a majority of nominators were so sure Affleck was in that they spent their votes on longshots, such as "Beasts of the Southern Wild's" Benh Zeitlin and "Amour's" Michael Haneke.
CNN: Oscar winners: Analysis of who won