McIlroy recovered from an early bogey in his third round at The Renaissance Club to rattle off four birdies in the space of five holes, only to drop shots on the 11th and 12th on his way to a three-under-par 68.
At 11 under par McIlroy would normally expect to be firmly in contention, but that was only good enough for a tie for 31st as the players continued to take full advantage of the lack of wind on a rain-softened course.
The four-time major winner will at least have a relatively early tee-time on Sunday before heading to his native Northern Ireland for the Open at Royal Portrush and joked: "The thing I'm happy about is that Belfast City (airport) closes at 9pm tomorrow night so I should get in before they close.
"I feel like I played better than the score suggests and that's been the story of the week.
"I heard a camera click over my second shot on 11 but I was more frustrated that I didn't back off, missed the green and made bogey and I let that bother me on 12 as well.
"The game is right there, I just need to go out tomorrow and shoot a good score and finish on a positive note."
McIlroy had not played since seeing his US Open challenge fizzle out with a disappointing final round at Pebble Beach and opted not to compete in last week's Irish Open, a tournament he had hosted for the previous four years.
"All I wanted to do was get a scorecard in my hand," the 30-year-old added. "It didn't matter if the winning score was 20 under or 10 under, I just wanted to play four rounds of competitive golf and I'm going to do that.
"I'll at least have a better idea of where my game is at going into next week, instead of having a week or a few weeks off and trying to figure it out once I get there.
"Maybe I would have wanted to have been a little bit sharper around the greens and do a little more practice, but overall I feel like my game is in really good shape."
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