McIlroy made a late push at Pebble Beach Golf Links on Sunday, briefly re-entering contention with four birdies in a five-hole stretch during his final round, before adding three more in four holes from the 11th.
The world No 2 signed off with a flawless 64, capped by a birdie at the last. Over an eventful week, he recorded 25 birdies and two eagles, but also mixed in three bogeys, three double bogeys and a triple bogey.
He finished tied 14th at 17 under par, five shots adrift of champion Collin Morikawa, who sealed a one-shot victory with a birdie on the final hole. McIlroy conceded that four costly holes proved decisive, denying him the chance of a winning start to the PGA Tour season.
"That's all I felt like I needed to tidy up, because the good stuff in there is really, really good," McIlroy explained. "Struck my irons well, drove it well for the most part. There was a couple of destructive tee shots yesterday [third round], but everything feels in pretty good shape.
"I wish I could have those four holes back this week. I played 68 really good ones and even you turn those three doubles into bogeys and that triple into a bogey, that's five shots and all of a sudden you're looking at a lead.
"All in all, some really good stuff this week and pretty encouraged going into next week for sure."
McIlroy opened his season with a tied-third finish at the Dubai Invitational, before struggling at the Hero Dubai Desert Classic, which prompted him to revert to the irons he used during his The Masters-winning campaign and had recently changed.
Asked which aspects of his game have improved the most of late, he said: "I think iron play, short game - I think those two areas. Maybe the driver as well even though, as I said, I hit a couple of destructive tee shots.
"I got one going on the wind on 18 yesterday and then the one on four [triple-bogey], but for the most part like I drove the ball better, which is good to see as well.
"I'm in a good spot. Get rid of those big numbers and I wouldn't be just right there, I would probably be in the lead."
Jacob Bridgeman survived a late scare from Rory McIlroy to secure his first PGA Tour title, edging out the Northern Irishman by a single shot at The Genesis Invitational.
Rory McIlroy followed up his opening 66 with an even better 65 to sit just one shot off the lead held by Marco Penge and Jacob Bridgeman at the halfway mark of the Genesis Invitational.
Rory McIlroy mastered the brutal conditions to post a five-under 66 and claim a share of the clubhouse lead at the weather-affected Genesis Invitational.
Rory McIlroy believes returning to his familiar set of irons could be key as he builds momentum ahead of another title push, starting with his defence of the AT&T Pebble Beach Pro-Am.
