OAKMONT -- Rory McIlroy is a great golfer. The U.S. Open is a great golf tournament.
What we're gradually finding out, though, is that they aren't necessarily great together.
Let's face it: McIlroy is never going to be chocolate to the USGA's peanut butter. If anything, he's banana -- every once in a while, it works.
Like five years ago, when he won the most un-U.S. Open-like U.S. Open in history, posting a score of 16 under on a Congressional course so soft that it remains an unseemly outlier in this tournament's history.
Since then, McIlroy missed the cut in 2012, finished tied for 41st in 2013 and T-23 in 2014 and needed a furious, final-round rally to squeeze inside the eventual top 10 last year.
Those results were at least trending in the right direction -- until this week, when he posted scores of 77-71 to miss the cut at Oakmont.
Maybe we shouldn't be so surprised.
Not long before this year's Masters, when McIlroy was once again eyeing the career Grand Slam, I asked him if it was easier or harder to need the anchor leg of that achievement at Augusta National. His answer revealed less about that tournament than it did about this one.
"I'm just glad I've won a U.S. Open," he offered with a smile. "Put it that way."
If we need some clues as to why McIlroy and the U.S. Open don't mesh, he provided plenty of them this week.
His opening round consisted of eight bogeys and just a single birdie in softer conditions that should've suited his style of game. Afterward, he admitted, "I've been struggling with my swing," then vowed to retreat to the practice range and figure things out.
When he returned for the second round on Saturday morning, it appeared he really had. McIlroy birdied four of his first seven holes, immediately forcing us to wonder whether Johnny Miller's much-celebrated 63 on this track could soon have some company.
McIlroy then drove the green on the short par-4 17th hole and proceeded to 3-putt for par. That's still a fine score in a U.S. Open, when anything in red figures might ultimately win this tournament. Instead, it seemed to deflate him. Playing the front side as his second nine, McIlroy double-bogeyed the third hole and bogeyed the sixth.
He came to the ninth needing par to make the cut, but he drove his ball into the bunker, couldn't extricate himself from there with his second shot and wound up posting another double. It was his fifth career missed cut at a major championship -- and third at the U.S. Open.
After the round, he declined all media requests, essentially adding another double-bogey to his list of lapses in judgment during the day.
We can only guess as to what was going through his mind, but within those details of his 36 holes lies the story of why McIlroy's extensive skill set doesn't lend itself to this golf tournament.
The U.S. Open is a slow, steady grindfest that lends itself to the Retief Goosens of the world. The lower your resting pulse rate, the better your chances here.
That's not McIlroy. His highs are too high; his lows are too low. When he gains some momentum, there's hardly a player with his shot-making ability in the world. When it starts going in the other direction, though, the roller coaster takes a deep, downward turn.
Before we move on, let's get something straight here: That's an explanation, not a criticism. McIlroy's propensity to make birdies in bunches has elevated him to elite status. Besides that one un-U.S. Open-like victory, he owns three other major titles and remains the world's third-ranked player.
His brand of golf works 51 weeks out of the year. It just doesn't work this week.
If this all sounds eerily familiar, that's because the same words have also been used to describe Phil Mickelson's overall performance at the U.S. Open. Now, Mickelson has owned his share of success in this event, with six career runner-up finishes, but those results are almost universally viewed through a prism of failure, the lone gaping hole on his otherwise sterling résumé.
McIlroy remains relieved that he has filled that spot. He will indeed win more major championships -- perhaps many more -- but the U.S. Open will always be his most difficult.
He proved that once again this week.