It is a job to know which was handing out the greater lesson, a brutal US Open course or life. A year ago he was the toast of Congressional, a 22-year-old supernova ripping up the tournament template with a pair of 65s en route to a record low score. How America loved Rory McIlroy, the tousled haired cherub with a murderous swing and the confidence to go for everything.
Twelve months on he left by a side door, wondering how a talent as deep as his could yield so little. A second round 73 was an improvement on the day before but not enough to avoid a fourth missed cut in five. He hit it well enough, he thought. A touch here, a bounce there and 10-over might have been plus five. From there he could have attacked the weekend.
The margins are minute in this business. And none is above a kicking on any given day. It is not something to be taken personally. And that is perhaps the hardest lesson to learn for it requires that McIlroy remove himself from the centre of the universe for five minutes and recognise that, as gifted as he is, he cannot take every course to pieces. Even the great ones have off days.
The post-round soundbites were encouraging. "Yeah it has been a tough six weeks or so. I realise that you have just got to keep working hard. It doesn't come easy to you all the time. It hasn't been the greatest run, but as I said, I still see enough good stuff in the rounds that it does give me hope that it's not very far away."
McIlroy did not suffer alone, not by a long way. World No 1 Luke Donald closed a shot further back on 11-over par. His wait to make any kind of impression at a major championship goes on. The sense that Donald cares too much is easily acquired. The promise to put the clubs away for a spell is well meant but hard to believe.
"I want to win one [major] more than any of you guys know. And obviously I'll continue to try and do that. I think I missed nine putts inside 10 feet [on Thursday] and just couldn't get the feel for the greens, the reads, the speed. And if I had putted a little bit better I could have ground out a score today and maybe been somewhere decently placed for the weekend. But it wasn't to be and I'm trying to learn from it and come back stronger next time."
The final member of the elite three-ball, Lee Westwood, escaped at plus five. If 2010 champion Graeme McDowell's instincts are right and par is good enough to win tomorrow, then Westwood is still a contender. He dashed from the 18th to watch the last knockings of England's Euro 2012 game with Sweden. An omen perhaps?
Were it not for three bogeys in his final four holes McDowell would have led in the clubhouse, just as he did two years ago at Pebble Beach. What is it about West Coast majors in the week of an international football championship and McDowell? At one-over after emulating the 72s of Donald and Westwood, he trades places with McIlroy in the role of heroic Ulsterman. "I feel like there's a fine line between 68 and 78. It was disappointing to drop three shots coming in, but that is what this course can do to you. You really got to give par a huge amount of respect. Very happy to be where I am. I think I played some really nice golf the last two days, made enough birdies to offset some mistakes, which I think is key."
The Pacific dawn in San Francisco is a thing of wonder. On a bad day you would take Grange-over-Sands. On a good day, and yesterday was one, there can be few better places on earth to start that day. Unless, that is, you have a golf club in your hand and a major to win. The United States Golf Association defended the course set-up, arguing that the game could tolerate at least once a year a championship that makes the players' pips squeak. Fair enough if the test is just, but as Westwood pointed out, a lot of good drives did not make the fairway on day one, and for golfers that is intolerable.
Overnight leader Michael Thompson shipped three shots in as many holes to come back to the field and surrender the romantic ticket to 17-year-old Beau Hossler, who went to the turn with a share of the US Open lead. A birdie at the 10th took Tiger Woods back to level par, one of the lead with eight to play. No one is running away with this.