Phil Mickelson was left to reflect on an "off year" after failing to break 70 at the Masters for only the fifth time in 21 appearances.
The three-time champion had fought back from a poor start to make four birdies in five holes in his first-round 71 that left him only five off the lead.
But further rounds of 76 and 77 ensured an early tee time for the final day, and he bogeyed four of the last six holes as a 73 left him way down the leaderboard on nine over.
"I just had an off year. I don't know what to tell you. I played poorly," said Mickelson, who hopes to turn around his form with the aid of coach Butch Harmon.
"Today was the first time that Butch and I had some good direction and I'll have something to work on these next two weeks before I play at Charlotte and The Players.
"But this was disappointing for me in that this is my favourite place in the world to play. And to perform like this is disappointing. I'm disappointed in myself because I expect a lot more of myself, out of my game and so forth this week."
Mickelson is now considering playing the week before next year's Masters after he opted to skip last week's Valero Texas Open.
"I would like to," he added. "I've got to look at that because the things I did this week to get ready I just wasn't as mentally sharp as I need to be. I've got to find another way to get ready for big events if I'm not able to compete the week before."