KIAWAH ISLAND, S.C. – Jason Dufner split with longtime swing coach Chuck Cook a few years ago. It was a decision based on a number of factors, including “logistics,” Dufner said.

Earlier this year, he reunited with Cook. That decision was based on performance.

“I had worked with him for a long period of time, kind of went away from him for a little bit and struggled. Kind of kicking myself a little bit for that,” Dufner said Thursday at the PGA Championship.

The ball-striking that he’s known for was back on display on Day 1 at Kiawah Island where he opened with a 1-under 71 and was four shots off the first-round lead. For Dufner, 44, working with Cook again has been familiar and given him something to look forward to as he reaches the later years of his Tour career.

Renowned as a student of the game with a keen eye for the golf swing, Dufner was asked if he’d put any thought into maybe becoming a swing coach when his competitive career was over.

“These guys are psychopaths, man. No. Never,” he smiled. “First off, there's no money in it, and second off, dealing with Tour players is a nightmare. You don't want to be part of it. That's just fact. Ask any of the teachers.”