A year ago, when David Hearn arrived at the first tee of the final round of the RBC Canadian Open to an impromptu serenade of O Canada from a throng of exuberant fans, he was in the midst of his best season as a professional golfer.

A few weeks earlier he had just missed out on his first PGA Tour victory when he lost in a playoff at the Greenbrier Classic. And on a sunny Sunday afternoon at Oakville’s Glen Abbey Golf Club, he stood two shots in front of his nearest competitor at his national championship. But as well as things were going for Hearn in 2015 — and by season’s end the now-37-year-old from Brantford would earn a career-best $1.8 million in prize money to rank 49th on the tour’s money list — a persistent distraction was never far from his thoughts.

A change to the rules of golf scheduled to take effect in 2016 was about to make it illegal to for players to use the so-called anchored putting technique Hearn had been employing for most of his pro career. The ban on this style of putting — wherein players brace the shaft of their putter against various bits of their torso — was about to make Hearn’s money maker a rule breaker.

Rolling the ball into the hole on the short grass, after all, was one of Hearn’s strengths. In 2015 he was the tour’s 27th-best putter as measured by strokes gained, an advanced metric many cite as the best measure available of relative prowess. So the knowledge that he’d soon have to scrap his broom-length putter for a different model while settling upon a wholly different technique was more than a little unsettling.

“It was a bit of a distraction all of 2015,” said Ralph Bauer, Hearn’s coach. “And you don’t need a lot of distractions for it to affect your play.”

That’s not to say the impending rule change will go down as the reason why Hearn couldn’t hold onto his final-round Canadian Open lead at the Abbey, where he ultimately finished third, two shots off the winning score. That result had a lot to do with the heroics of Jason Day, the world No. 9 at the time, who birdied the final three holes to ensure a victory that kick-started a remarkable late-season surge that included a win at the PGA Championship a week later and an eventual climb to his current standing as world No. 1.

Hearn and Day are slated to be in the field at this year’s edition of the RBC Canadian Open, which begins Thursday back at Glen Abbey. Other big names expected to tee it up include world No. 2 Dustin Johnson, Jim Furyk, Ernie Els, Vijay Singh and Graeme McDowell. And Hearn will be joined by 11 other Canadians, among them fellow Olympic-bound teammate Graham DeLaet, who’ll arrive in Oakville fresh off Sunday’s final-round 63 that vaulted him into the top 10 at the PGA Tour’s Barbasol Championship. Hearn shot 67 on Sunday at the same tournament, which ran concurrently with the Open Championship at Troon, to put himself into the top-20 mix.

“It’s great to have the world No. 1 and No. 2 at the RBC Canadian Open,” Hearn said. “Our national championship still holds a lot of respect for the players on the PGA Tour.”

Hearn spent considerable time last season readying for the putting rule change by spending off-weeks experimenting with alternative techniques. The test-driving of various options continued into the early part of the 2016 season. For a while Hearn tried the combination of a cross-handed grip on a so-called counter-balanced putter, which worked well enough but didn’t deliver sufficient results under pressure. More recently — Bauer says since the Honda Classic in late February — Hearn has gone to the arm-lock technique popularized by PGA Tour player Matt Kuchar, albeit with various tweaks to the method’s finer points.

“Most people copy what Matt Kuchar’s comfortable with as opposed to finding out what they’re comfortable with,” Bauer said. “What works for Matt Kuchar won’t necessarily work for other guys.”

Whatever Hearn is doing is working well enough for him. While his current campaign hasn’t been as fruitful as 2015, he said in a recent interview that his putting stats since he went to the arm-lock style have been comparable to his work with the anchored stick a year ago. Bauer goes a step further.

“He’s better now with this putter than he was with the long putter,” Bauer said.

It’s not the only facet of his game on the upswing. Heading into play this past weekend Hearn was leading the tour in proximity to the hole on approach shots. But depositing the ball in the hole is an essential skill. And as much as putting technique can be a moment-to-moment matter — in Sunday’s final 18 holes at the Open Championship, for instance, runner-up Phil Mickelson changed mid-round from the claw grip to a conventional one — Bauer said it’s a good thing that Hearn has put the uncertainty of his post-anchoring-ban existence behind him.

“A good putter’s a good putter,” said Hearn, speaking of the player, not the piece of equipment. “Like, my mind didn’t change. My body didn’t change. The technique I had to use has changed. That’s what you have to work through.”

A year ago at Glen Abbey, when Hearn arrived for the final round with that two-shot lead, his flat stick had been working better than anyone’s. In the opening 54 holes he’d been the best putter on the grounds, bar none. And after he birdied the opening two holes on Sunday, it looked for a long moment as though Hearn had a great chance to become the first Canadian to win the national championship since Pat Fletcher in 1954. But his game cooled that day. He stumbled into four final-round bogies and made just one back-nine birdie before Day went on his winning blitz.

After it was over, Hearn pondered Day’s tournament-winning spree admiringly before uttering a vow: “I’ll do that one day,” Hearn said.

This coming Sunday would be as good a day as any to make good on those words, but there’s plenty of short grass to navigate between here and there.

“The more times you put yourself in that position, the more successful you’re going to be,” Hearn said. “But I know my game’s getting close, and when I do get back there I’ll be able to draw on those experiences and how I felt, and I think the result will be different next time.”