Phil Mickelson had a decent 2012 Masters over 72 holes. His 8-under score was good enough for a tie for third place, and he was 2-under par on the back nine on the final day. Out of context, this makes it sound like Lefty did his best and put in a solid performance, but just couldn't keep pace with Bubba Watson and Louis Oosthuizen.
But then we apply the necessary context, and the story becomes very different. That necessary context is his absolutely hilarious triple bogey, which is hilarious because it's all his fault. It's agonizing to watch golfers make terrible scores when they're getting bad breaks or their shot is just off, but that wasn't the case for Mickelson at all.
With his ball buried in mud, Mickelson had the option to re-hit his tee shot on the third hole. If he hit a solid tee shot, he would have had a chance at a bogey, and likely would have ended up with a double bogey. He made birdie on the hole on Friday, so a four certainly wasn't out of the question. Almost every other golfer on tour would have opted to re-take their tee shot. Lefty decided to take some right-handed hacks at a mud ball and only made six because his fifth stroke was a spectacular bunker shot.
Mickelson was excellent after that hole, but that one hole killed his chances to win The Masters. It was a great reminder of how good Mickelson thinks he is. Confidence is a good thing, but hacking at a ball in the mud indicates that one has crossed the line from confidence to arrogance. That's probably why everyone calls him FIGJAM.