The 42-year-old finished tied for 54th at Augusta after shooting nine-over par following his scores of 71-76-77-73.
However, the American is refusing to get too down about his slump and believes that it just was not his time to shine.
"I just had an off year," said Mickelson. "I don't know what to tell you. I played poorly.
"This was disappointing for me in that this is my favorite place in the world to play.
"This is my favorite place to be, my favorite tournament and one I look forward to the day after it ends. And to perform like this is disappointing."
Mickelson is a three-time champion at the Masters, with his last victory coming in 2010.