Rahm won the points-based player of the year award from the PGA of America, and it was that birdie putt on the 18th hole at East Lake that made the difference.
Rahm finished with 75 points, with Bryson DeChambeau coming in second at 70 points.
Rahm received 30 points for his U.S. Open title this summer, along with 20 points for leading the PGA Tour money list and 20 points for winning the Vardon Trophy for the lowest adjusted scoring average.
And while he was runner-up to Patrick Cantlay in the Tour Championship, the PGA of America recognizes the actual score at East Lake. Cantlay started with a two-shot lead at 10-under par because he was the No. 1 seed. Rahm started four shots behind as the No. 4 seed.
For the week, Rahm and Kevin Na finished at 14-under 266. That means they split the 10 points awarded for a regular PGA Tour win.
DeChambeau had 30 points for his U.S. Open last September, 10 points for winning at Bay Hill, 14 points for being fourth in scoring average and 16 points for being third on the money list.
On the par-5 18th at the Tour Championship, Rahm hit a 5-iron that just ran through the back of the green. He needed to chip in to have any chance of forcing a playoff against Cantlay, who hit 6-iron to 12 feet. Rahm’s chip narrowly missed, leaving a short birdie putt.
That allowed him to tie Na at 14-under, giving him the five points that put him atop the points standing for the PGA of America award.
The PGA Tour award for player of the year is a vote of the membership. The ballot went out Tuesday and included Rahm, Cantlay, DeChambeau, Collin Morikawa and Harris English.
Justin Thomas won the PGA of America award last year, while Dustin Johnson was voted PGA Tour player of the year.
Rahm’s adjusted scoring average was 69.3. Johnson was second at 69.62.