Another major, another major run by the utterly unflappable Jordan Spieth

SHEBOYGAN, Wis. — Explain Jordan Spieth, please, without using the word “intangible.” There he is on the leader board again at the PGA Championship, with that cipher of a name that looks misspelled and the talent that defies analysis. It’s hard to define a player with no discernible fingerprints, other than the ones he puts on silver trophies.

With a round of 67 on the precarious ledge called Whistling Straits, the 22-year-old Spieth jumped into contention in his fourth straight major championship of 2015. This can’t continue, surely. The boy has to get tired some time. Except Spieth keeps playing like a man, while some people acted like kids in the PGA’s second round Friday. Phil Mickelson slid down a hill on his butt like he was riding a saucer, and John Daly decided to wing a club into Lake Michigan in mid-tantrum. While they were fooling around, Spieth stalked up the leader board with a half-dozen birdies that put him at 6-under-par 138, just three strokes out of the lead when play was suspended.

[Lingmerth has lead as storms halt PGA’s second round]

Spieth was hardly the only player with a hot round on a day that was relatively still and sun-baked until play was halted by a late-afternoon violent storm: Jason Day and Matt Jones were the leaders on the course at 9 under with Justin Rose at 8 under. But none of them are attempting to do what Spieth is: become just the third man to capture three of the four major championships in a single season, along with Tiger Woods (2000) and Ben Hogan (1953). It’s an almost unthinkably difficult feat for any player, much less someone so young, and his ability to hit yet another performance peak suggests what Spieth’s talent is really made up of: a voracious competitive mind.

“I feel good,” Spieth said. “I got a chance to win a major championship. Just thinking about that gets you enough adrenaline so that there won’t be any issues.”

It’s obvious what makes top-ranked Rory McIlroy great, the combination of force and liquidity in his swing, which kept him in the hunt at 2 under after some cliff-side adventures that included a double-bogey and an eagle, the result of rustiness from his extended absence after rupturing an ankle ligament. It’s obvious what made Woods an all-timer, the meeting of soft hands and iron focus, before he messed himself up so badly that he can’t seem to make a cut in a major championship.

But Spieth? Scan him up and down, and you search in vain for a defining feature. The colorless hair, the medium build, the solid repeating mechanism that is his swing, none of it explains him. It’s not until you get to the squinty Clint Eastwood eyes that you find a clue. Maybe the closest you can come to explaining what he does on a golf course is to call him a great mentalist. You get the feeling that when he’s zeroed in, he can bend spoons by looking at them. Which is sort of what he did with a hole-out from the bunker on the par-4 18th hole, one of the hardest positions on the course, that galvanized his round.

[Forget Tiger vs. Phil — it’s Spieth vs. McIlroy now]

Spieth was deep in a jigsaw bunker adjacent to the green and up against the back lip. He had to come partly across the ball and carry over some long grass to the green. He knew if he hit it wrong, he would catch it thin, and it was “probably a double bogey.”

All he did was hit it just right, a high lob that touched down softly and glided into the hole. “I just struck it absolutely perfectly,” he said. He called it a little bit lucky, but it wasn’t. He knew exactly how to play out of that the bunker, which had extra deep sand in it, because he had done thorough homework by talking to caddies about the course. He knows where he is going on every shot and every contour of a course. The result is Spieth now has 16 hole-outs this season.

It’s hard to find another statistic that stands out. On the PGA Tour he’s 76th in driving distance, 85th in accuracy. He’s 55th in greens in regulation. He’s 36th in total putting. Though he has a reputation as a brilliant putter, he’s not great from short- and midrange — he ranks just 172nd from 10 feet. His strength is longer range: He ranks second from 20 to 25 feet.

Here’s all he is really great at: scoring. He’s a killer opportunist — he ranks first in birdie average, second in birdie conversions. He is also great at limiting his mistakes, seventh in scrambling.

“He has harmony between visualization and execution,” says Brandel Chamblee, the Golf Channel’s superb analyst.

There is another statistic to trace the outline of Spieth’s emerging talent, which, by the way, is still in relative infancy. Think about the number of times you’ve seen Spieth follow a bogey by making a birdie. He’s the king of “bounce backs”; he does it 48 percent of the time. That tells you two things: how much all-around game Spieth has — “You can’t find a spot on the golf course where he isn’t comfortable,” Chamblee says — and also the size of his fighting heart. He’s especially good at it in majors. In the 14 rounds he has played in the majors this season, he has responded to bogeys with birdies a dozen times.

[A near-miss for Spieth at St. Andrews]

Along with that quality of mind comes temperament. “The situation absolutely doesn’t bother him,” Chamblee observes. Somehow Spieth has avoided becoming drained or enervated or suffering a letdown from the effects of all that winning — something even British Open champion Zach Johnson couldn’t avoid, shooting 75 on Friday. Spieth might have been knocked off stride by his new fame, the constant pumping of his hand everywhere he goes, the incessant requests for cellphone photos, the bleached lights of TV cameras in his face before and after every round. But he hasn’t been.

He has paced himself with bouts of pure normalcy. After he returned from Scotland he celebrated his 22nd birthday sitting by his pool in Dallas and drinking beers with friends. He has the gift of perspective, of wanting it just enough but not too much. He plays the game as a game, not a labor, and from a place of seemingly emotional security.

“The way the year’s gone, I approach each event as if it’s the only event of the year when I stand on the first tee,” he said. “So that gets me through it. . . . Just looking at the board, grinding it out, I don’t feel any fatigue. I’m sure at the end of this year, it will be nice to sit back and hang the clubs up for a couple weeks, but until then we have got a lot to play for.”

For more by Sally Jenkins, visit washingtonpost.com/jenkins.