In chess, it is said that it is easier to reach a winning position than to win from a winning position. David Silva managed the first part surprisingly well, was extremely happy with the position over the board and quickly agreed to a draw in 41 moves.
Playing black, Aronian did try to create some chances by exchanging a rook for a bishop but Silva was equal to the challenge and gave nothing away. Soon, Aronian faltered on the 25th and later on the 36th, too. But Silva seemed more focussed on keeping his position solid.
In fact, in a position where the draw was agreed, Silva could have built on the advantage had he continued by exchanging the queen. Obviously, he must have thought of the queen-exchange but did not have a clear-cut winning plan. This is where the difference in their rating strength - 460 points to be precise - showed up.