Sunday, he delivered on that inspiration, winning the World Challenge presented by Northwestern Mutual for his first victory since ... his last victory here at Sherwood Country Club two years ago.
"It's been too long," McDowell said following a final-round 68 to win by three over Keegan Bradley. "It's been a hell of a two years since I sat here as a winner.
"We like to say that it's all about the processes and going through the motions and trying to get better. But let's be honest, we all measure ourselves by the wins. I can say that now."
The last time McDowell won here came on the heels of a dream season that included winning his first career major championship a few hours up the coast at Pebble Beach and securing the winning point at the Ryder Cup.
In the months that followed, however, McDowell's game got lost in the process as he struggled to adapt to his newfound stardom. The following season, McDowell recorded just three top 10s on the PGA TOUR and missed the cut in six of his 16 starts, including in three of the year's four majors.
This season had its moments -- McDowell finished second at the Arnold Palmer Invitational presented by Mastercard and the U.S. Open -- but he had just two other top 10s, never threatening to win.
Meanwhile, McIlroy was contending seemingly every time he teed it up, especially early in the year when he finished in the top 5 in each of his first five starts before ending the season with five worldwide wins, including two FedExCup Playoffs events another major championship, and the top spot in all of golf.
"I always talked about Rory being my little radar blocker; let him take all the press and accolades and I just kind of slipped under the radar," McDowell said. "I won the U. S. Open doing that.
"But what he's doing, you know, it's tough not to be inspired by that. In my career I've sort of rubbed shoulders with players better than me, players I feel like I can learn things from and people that can motivate me. I'm not sure what small part I've had in his career of motivating and mentoring him. But he certainly motivates me for sure."
It showed on Sunday.
On a soggy week at Sherwood Country Club, McDowell at one point went 41 holes without a bogey. In all, he made just three bogeys. His round Sunday also marked the 10th time in 12 rounds at Sherwood that he has shot in the 60s. In three trips here, McDowell has won twice and finished second the other.
"Just when I thought maybe I'd have a chance, he'd hole a putt or hit a chip like he did on 17 (when he got up-and-down to save par)," Bradley said.
His California dominance aside, that wasn't the only clutch shot McDowell made in the final round.
After McDowell bogeyed the 13th and Bradley made birdie to cut a four-shot deficit to two, the Northern Irishman never allowed Bradley to get any closer.
McDowell saved par with a two-putt from some 75 feet on the 14th, then followed with the chip shot on the 17th that nearly tumbled in.
One hole later, McDowell made birdie from 6 feet to seal the already decided outcome.
"You know, he's a champion so I don't expect anything else out of him," Bradley said.
And finally McDowell doesn't either.
"I characterize these last two years, the first eight months just an absolute writeoff," he said. "These 10 weeks are huge for me really just from a resetting and recharging and resetting my goals and getting ready for a big year next year. This will give me some nice momentum going into the offseason."
With it, McDowell will take plenty of confidence, which should come in handy against McIlroy.
"I'd love to see him down the stretch somewhere, some Sunday afternoon," McDowell said. "That's all I can say."