Two minor pieces beat a rook only when the rook's king is on the edge and cut off; with the kings active and the pieces protected, rook versus bishop and knight is a draw. The rook side avoids pins and forks and keeps the king central.
Rook against two minor pieces (bishop and knight here) is a draw in the great majority of positions. The minor pieces cannot force mate against a central king, and the rook cannot win a protected piece. Both sides have work to do, but the balance favours a draw.