World number one Rory McIlroy admitted he was tired after failing to challenge at the Tour Championship on Sunday.
The Northern Irishman, who shared the overnight lead with eventual winner Billy Horschel, never got going in Atlanta.
McIlroy carded a one-over 71 in his final round to finish three shots adrift of Horschel, who was 11 under as he won the FedEx Cup.
The four-time major winner said he was feeling the effects of a long and successful season, which included The Open Championship and US PGA Championship crowns.
"It's been a long four weeks," McIlroy said.
"If I had to do it all over again, I probably would have taken a week off somewhere in this stretch of tournaments.
"It's tough because ... these sponsors that are sponsoring the tournaments and the FedEx Cup play-offs, they're putting up an awful lot of money to get the best players in the world there to their event.
"Not that you feel obliged, but you want to support the events and you want to show up and give the sponsors something to be happy about and proud of."
McIlroy birdied the fourth hole before starting to struggle, double-bogeying the sixth and bogeying the ninth.
Bogeys at 10 and 11 saw him slide out of contention before he regained some form late on with a hat-trick of birdies.
McIlroy, who finished third in the play-offs, said it had been a difficult day and he was unable to will himself to go again.
"I just got really frustrated and just couldn't muster the energy to try and get something going again," he said.
"And even when I was hitting good shots, I was hitting bad putts."