Day started the season with a win in his native Australia, claiming the ISPS Handa World Cup of Golf in November.
The 26-year-old backed that up with a tie for ninth at the Northwestern Mutual World Challenge and second at the Farmers Insurance Open.
Day also took out the PGA Tour's WGC-Accenture Match Play Championship before a thumb injury derailed his campaign.
However, the world number nine is back to full fitness and after sharing 15th spot at the US PGA Championship, Day finished two strokes behind American Hunter Mahan at the FedEx Cup play-offs opener in New Jersey.
"I definitely had a shot today," said Day, who improved to seventh in the FedEx Cup rankings. "It's so close. Like it's just in my fingertips and I can touch it.
"But Hunter played that much better than all of us and he deserves to win. When you play great on the back nine on a Sunday in a play-off event, you're doing something right.
"He's had his struggles a little bit this year. He's pretty high up in the FedEx and [that's saying something] for him because the guy makes every play-off event in previous history.
"But the way he played you've just got to take your hat off to him because he played well to win the tournament.
"I didn't lose it, which was a good thing. I played well, tried my best and wasn't good enough."
Day added: "I feel like I'm peaking at the right time, I'm trending in the right direction. I really want to give it a shot at winning the FedEx Cup.
"That's the ultimate goal, and you can't do that without winning tournaments."