Australia's only weekend contender could not buy a putt in a deflating, birdie-free three-over-par round of 75 at Augusta National on Sunday.
Day was tied for fifth and just three shots behind after the third round, believing he had a chance to finally claim an elusive green jacket 15 years after finishing runner-up on debut.
"Actually played okay. Just didn't take advantage of (holes) two and three," Day told AAP.
"You get birdies there, that obviously changes the storyline a little bit."
A wretched double-bogey on the par-3 seventh realistically cruelled Day's chances of featuring down the stretch.
"Actually hit 13 greens and played pretty good," he said.
"Just didn't capitalise on any opportunities. Putted actually quite poorly today.
"So a little unfortunate, but just how it goes. I mean, I'm pretty positive about my game."
Day's silver lining is an invite back next year after the former world No.1 made a huge sand save for par on the last to finish a respectable equal 12th alongside five-time major winner Brooks Koepka and past champions Jordan Spieth, Patrick Reed and Hideki Matsuyama.
"Obviously it's nice to be able to come back next year but a little disappointing," he said.
"I know I can play well around here. It's just obviously when you get the opportunities, just take them.
"Sometimes you have to take them. Sometimes you have to take some unnecessary risk and sometimes you got to take a step back and play the way you need to play.
"Unfortunately I just didn't play the way that I needed to."
Compounding Day's frustration was seeing his English playing partner Justin Rose tie for third after starting the day on the same score and grabbing a two-shot lead at one point early on the back nine.
"Obviously I was watching Rosey on the front side and he got off to a dream start," Day said.
"That's kind of in my mind where I saw a lot of birdies - minus five - what he did.
"But a lot of the birdies that he made I saw those and just didn't get myself in the position."
Adam Scott, the 2013 champion and only other Australian to make the halfway cut, also cut a frustrated figure after sharing 24th spot at two under after a final-round 70.
"I just never really got it going. I don't know, overall, I guess I blame the putter," he said.
"I just didn't get it rolling on the greens and take advantage of some of the good golf and get any real momentum going.
"The last three holes on Friday kind of really shut me out of a chance yesterday to get back in it like everyone else got back in it."
Next month's PGA Championship will be Scott's 99th consecutive major as he closes in on an incredible milestone that no other active player can boast of.
But the 45-year-old ex-world No.1 still yearns for more.
"The main thing is really that I probably dreamed loftier goals than were maybe possible when I was a kid. Thanks, Tiger," Scott said.
"If I wrapped it all up now, I feel like I'm really not that content and I would hate to finish my career not content.
"I've put in a lot of good stuff, but I feel like there is something big left in me still.
"So it's worth pushing."
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