A diifferent way of looking at this, is that when the pressure became the greatest, Dufner underperformed the standard he had set. He hit the ball better than anyone all week. He had played the last four holes without a bogey the first three days. I dont expect him to continue to play like that for four straight days of a major championship regardless of whether or not he is in the lead. His ball striking definitely took a sharp turn south no matter how many waggles he wagged at address. The contrast between how he had played and how he played on the last four holes was stark, but it doesnt have to be considered a choke. Every player struggled on the way in, including Bradley with his triple on 15, and its not like he stuck it on 17, he canned it from the west coast on some of the toughest (and best conditioned) greens that I've seen in recent major championship history. Choking is just a matter of persepective on where you make your mistakes. You four putt like O'Hair did early in the round its going to cost you. How many of us have had rounds that would have been "our best ever" if we hadn't had those terrible holes in the first 3. I think the pressure builds, and some players are considered clutch, but has anyone had worse luck than Dustin Johnson? I dont believe that he is a "choker" either.