SOUTHAMPTON, N.Y. — While Patrick Reed was winning the Masters in April, Brooks Koepka sat at home in Florida, nursing a left wrist injury that had kept him off the golf course for most of the previous four months. He wouldn’t be cleared to take full swings with his wedges or irons until the Monday after his friends and fellow golfers had departed Augusta National.

That didn’t leave much time for Koepka to prepare to defend his 2017 United States Open title. But his swing coach, Claude Harmon III, knew Koepka would be fine when he saw that he was glued to the television, watching the end of the Masters instead of the beginning of the Major League Baseball season.

Koepka has “never really been a golf nerd,” Harmon said, but not being able to play changed his relationship to the game. “He watched the Masters, and I really believe he fell in love with golf again,” the coach said.