If Dustin Johnson isn’t careful, the world will see right through that devil-may-care disguise he’s been wearing for more than a dozen years. If he keeps showing such determination to add new titles to his portfolio, as he did at this Tour Championship, we’re going to start mistaking him for someone who takes this golf thing as serious art.

“Yeah, I was nervous,” Johnson said of how he felt on the first tee Monday. Even though he sure didn’t show it.

“I always get nervous because it means something,” he said.

But it was with an outward cold-blooded efficiency that Johnson closed out a FedEx Cup title Monday at East Lake, rousing a nervy par-save here and a for-good-measure birdie there on No. 18 to hold off Justin Thomas and Xander Schauffele by three shots. Any perceived drama at the close was illusory.

He did not shoot the lowest score here this week – that was Schauffele, who loves this place like a blood relative. He went 67-65-67-66 (15 under), compared with the 11 under of Johnson and Thomas, but could not overcome the advantage Johnson had coming in as the FedEx Cup points leader.

It’s been such a big month for Johnson that he should be listed on the Dow Jones by now. With the $15 million he earned Monday added atop what he made by finishing second at the PGA Championship and first and second in the opening two playoff events, that’s $18.7 million he has cleared since mid-August.

Insert obligatory money-is-secondary quote here: “Well, at this stage of my career I’m fortunate enough where I don’t need to think about (money). It’s all about winning and the trophies. The money – I don’t really care about that. I want to win tournaments, and I want to win trophies.” This was the 23rd big PGA Tour trophy he has claimed.

To think, when golf took its coronavirus break in March, Johnson ranked 111th in FedEx Cup points. And when he arrived here, he was the leader and placed atop the Tour Championship leaderboard at 10 under before he hit his first shot. Dustin Johnson getting strokes? That’s like the wolf getting three steps on the lamb.

But those are the rules of this jungle, and in a way that made Johnson want this title all the more. He has been to this event 11 other times, had some outside shots at winning the big prize, but never came like this year as the clear favorite.

The easygoing Johnson doesn’t exactly reek of determination, but it was written all over his past four days at East Lake. He wanted it. He went after it. Don’t get in his way.

“Obviously today I was in control of winning the trophy or not,” Johnson said, contrasting his position to other East Lake visits. “If I played well, I was going to win. If I didn’t, I wasn’t going to. I like that situation a lot better.”

Playing partner Schauffele surmised Sunday that he could start with three birdies and Johnson would barely blink. Well, he did get two in his first three holes, and indeed, Johnson was as unmoved as a Sphinx.

Entering the final round with a five-shot lead, Johnson saw it shrink a couple of times to as little as two shots. But he responded to each challenge.

The day turned irrevocably Johnson’s way on the 13th hole, with Schauffele just two back. Johnson staring down a 21-foot putt to save par. His putt hurried across the green and was going either to find the hole or skitter to the Avondale MARTA station. It banged off the back of the hole and dropped.

“That was a big swing,” Schauffele said. “He’s here to win the tournament. He made that putt, which I didn’t. That was a pinnacle moment, I think.” Schauffele’s own 23-footer for par went wanting.

“Yeah, that putt was definitely kind of the turning point for me there on the back nine,” Johnson said. “You know, obviously it gave me the confidence and kind of kept the round going in the right direction. I hit some really quality shots really the rest of the way in. That was a big putt.”

Overcoming back-to-back bogeys on Nos. 7 and 8, Johnson was 1 under and bogey-free the closing 10 holes. Thomas and Schauffele were good – both shooting 66 on Monday. But not quite good enough once Johnson decided he wasn’t going to give back any more strokes.

Thomas can testify to the Johnson drive that no one sees. He played with him at the Memorial, when Johnson shot 80-80 and missed the cut. The next week, Johnson shot a first-round 79 and withdrew with reported back pain.

“I’ve never seen him as lost, anywhere remotely close to that lost,” Thomas said of Johnson’s state only a few months back. “He was grinding his butt off. He was putting so bad and playing so bad. But he never gave up. He wasn’t quitting. He was just trying to find it out there. Then next thing you know, what, two months later he’s the FedEx Cup champion and running away. I think that’s all you need to know about golf right there.”

It’s something to know about Johnson, for sure, and to factor into an otherwise low-key image.

He’s a major winner. A winner on Tour each year for 12 seasons. Now a FedEx Cup Champion.

Legacies like this can’t spring from indifference. They only grow in the rich loam of talent and effort and require constant tending. You don’t just shamble into a career like this.