By resources i mean things like going into a position that gives your opponent an incredibly small advantage but is hard for them to play. It's one of the best ways to win games. it's hard work to find those lines, and he's been doing it for so long at WCC level it's not surprising that he's tapping out against someone he's already beaten. if you use a line in the WCC, it becomes very risky to use it again - because if your opponent studied it and plays it correctly then all you've done is make it even harder for you to win the game.
to reach 2900 he has to win games, not tie