Justin Rose simply outplayed him. And Mickelson deserves credit for putting himself in that position again at age 43, but the fact is he faltered on the last six holes.
Halfway through 2013's set of majors, this is the theme: There are so many talented players such as Adam Scott and Rose on the PGA Tour, it's inevitable that some of them would start learning how to win majors.
As Tiger Woods is unintentionally proving, being stuck on 14 major tournament victories, these things are tough to win. The final round at Merion Golf Club was another case of U.S. Open pressure taking a toll on so many players. Rose came through with some great swings when he needed them.
Mickelson's career will be somewhat incomplete if he never wins a U.S. Open, but that's only because he has been in contention for the title so many times. A victory Sunday would have become a capstone, certainly. But these wins are never awarded as lifetime achievements. They have to be earned over four days, and his closing 74 was not good enough.
As for Woods, he's now gone five years since his last major victory, meaning that 20 tournaments have been staged. He didn't play in all of them, but that period still represents a bunch of missed opportunities in his bid for a 15th win that would put him closer to Jack Nicklaus' record of 18.
The way Tiger was playing earlier this season, nobody would have been surprised if he had won the Masters or the U.S. Open or both. But he failed to come close in either event, and who knows when that 15th title will come, if ever?