In games against both Adams and Jones, Nakamura came within a hair of winning. Every time I thought he would win the game, those guys defended like madmen and came up with resources. He was a pawn up in both, but wasn’t quite sufficient to win.
Top-level chess must be very frustrating. It takes so much to win a game!
You bet! Once you get through all the tricks and traps and have to play as accurately as Shredder or Houdini, things get real in a hurry. The slightest misstep and it’s game over; that has to be stressful. Makes me almost wish I’ll always be a class player. 
You don’t even need to be a Grandmaster to experience the frustration of drawing against the resourceful defense of your strong opponent in a position you thought was winning. 
Round 3 in London had two games that had to be frustrating for the players who couldn’t break through.
I watched Hodgson and Short go through the Kramnik-Carlsen draw. All they could really say was that Kramnik somehow lost his way somewhere around move 30-35, but no one could come up with a better plan than what he played.
And Anand probably should be +2 instead of +1, but elected to play it safe with his one extra pawn against Aronian instead of snapping off another pawn with 26 … Nxa3 and potentially allowing an attack. Normally, Anand’s choice of 26 … Nd6 would win. Aronian, of course, is not exactly normal, and held the draw.