Usually, two minor pieces are better than a rook – a rule of thumb every beginner learns quickly. However, in practice things are usually more difficult. Sometimes a rook is better than the minor pieces and sometimes the two minor pieces are indeed theoretically better but cannot win because the position is too blocked.
This happened in the game between Caruana and Duda. White had the two minor pieces but it was not easy to see how he could enter Black's position. In the game Black made an error that allowed Caruana to demonstrate how White can win such positions, but after taking a very close look at the position Zoran Petronijevic came to the conclusion: "The position is even – White cannot penetrate". In practice, the two minor pieces won the game, but theoretically the rook could have saved a draw.
