The 24-year-old carded a 77 on day two of the competition, but fought back over the last two rounds to finish on even par and joint-eighth thanks to a three-under final round of 69.
McIlroy told Sky Sports News: "I sort of got it going a little bit round the turn... 13 is where it de-railed me a little bit. I only had a nine-iron into the green, hit a good shot straight at it but it came up short.
"All of a sudden you turn that into a four and 15 into a four, that's four shots and you think of the shots I've left out there this week.
"I'm going to look back at what might have been, the signs are there that my game is there from tee to green, if I can just convert some of the chances I'm giving myself my season looks like it could be a really good one."
McIlroy bested his finish of 2011 when he placed 15th in the tournament.