"I wouldn't say that I was surprised by the way things went for me this week. I played a bit like that last week and lost a bit of confidence in my game."
A downbeat McIlroy hinted at a break from the game after a disappointing five-over-par 77 saw him miss the cut by four shots.
The young Northern Ireland player carded a double-bogey at the seventh hole and bogeys at the eighth, 14th and 16th during his second round.
Dejected McIlroy to take break
"I'm just not myself at the moment and this is the sort of golf course that makes your errors look even worse when you're slightly off," said McIlroy.
"I don't know what is going on - I just need to take a bit of a break and come back with a refreshed attitude.
"I think that I need to go home and get my head sorted," he added.
"I'm getting frustrated very easily and getting down on myself."
Vijay Singh was a former champion who failed to make it to the final two days, with Ian Woosnam, Ben Crenshaw and Bernhard Langer also among those to heading home.
There were only three shots separating Sandy Lyle and overnight leader Fred Couples overnight but it quickly turned into a morning to forget for the Scot who shot a nightmare 86.
The 52-year-old's horrendous front nine of 46 - only three less than the worst in the tournament's long history - was followed by a triple bogey six on the 12th and a fourth double bogey of the round on the 14th.
"I'm battered and bruised," said Lyle.
"You have to smile. It got beyond a joke. I lost my rhythm completely and just couldn't regroup.
Lyle endured a dire second round after his promising start at Augusta
"For the first nine holes I thought I was playing with a square ball."
Debutants Simon Dyson and Chris Wood finished six over and 10 over respectively after rounds of 73 and 76 and also failed to make the cut.
"Watching on television you think it can't be that hard, but it really is," said Dyson.
"If somebody had said I would play like I did I would have taken it, but the wind probably cost me 10 shots."
However, their efforts were brought into some kind of context after a truly woeful display from former US Open champion Michael Campbell.
The New Zealander, who has not made a halfway cut for six months, improving only two shots on his opening 83, and that meant a 20-over-par total of 164.
"Mentally I'm not there and maybe I should get away for a month or six months - who knows; I need to get myself sorted out," said Campbell, who only five years ago got the better of Tiger Woods at Pinehurst.
"Michael Campbell should not be shooting these scores. It's just not working.
"I knew this week is a bit different, if you don't have your 'A' game it makes you look like an idiot, but this is pretty much the worst I have felt since I turned professional."
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