Endgame Imbalance
rook + bishop vs bishop + bishop (with additional pawns) can be a tough endgame. i've recently found myself in that predicament and managed to win through my opponents blunder. after the game, i did put one of the positions into a endgame tablebase (well, a position i could have reached if i had traded down some pawns). with perfect play it would have been a draw according to the tablebase.
therefore, i would suggest that white has to take out some of black's pawns in order to have a good chance. i could be wrong though.