With Jones’s help, Koepka in time came to see that his outbursts were an obstacle in his path to becoming a champion golfer. He won his first event as a senior, then added two more titles by the season’s end.
“He can take tough love,” Jones said. “You’d ride him, and he’d thank you for it.”
The transformation that began in Tallahassee was on full display down the stretch on Sunday. Koepka made three birdies in a row starting at No. 14 to distance himself from a fast-charging Hideki Matsuyama and a steady Brian Harman. Matsuyama and Harman finished at 12 under, which would have been good enough to win 115 of the United States Opens that have been contested, but not the 117th. They finished four strokes behind Koepka, who tied Rory McIlroy’s tournament record of 16 under in 2011.
“I had an opportunity today, and I didn’t get it done,” Harman said afterward. “But at the same time, I don’t feel as though I lost the golf tournament. I think Brooks went out and won the tournament.”
In four rounds, Koepka missed seven fairways and 10 greens. His machine-like efficiency was matched by his programmed waves to every made putt. His emotions on the course ran the gamut from calm to cool.
“He’s just really, really chill,” said Koepka’s caddie, Ricky Elliott. “Brooks could sometimes do with a little kick, like are you awake yet? He’s as calm as it gets, really, to a fault sometimes.”
Koepka, 27, came into the Open with one PGA Tour victory, in 2015, but he outperformed his résumé in the majors. He tied for fourth at the 2014 United States Open and the 2016 P.G.A. Championship and tied for…