The 24-year-old from Oban had a second successive top-20 finish in a major in his sights after bursting out of the blocks with three straight birdies on the Pete Dye-designed Ocean Course on the South Carolina coast.
After then dropping shots at the fourth, seventh and 13th, he then got back into red figures for the day with a birdie-4 at the 16th before a double-bogey 5 at the penultimate hole left him having to settle for a 73.
That gave him a five-over-par 293 total, finishing alongside Rory McIlroy after maintaining his 100 per cent record of making the cut in all five majors he’s teed up in.
“I feel like I played good,” said MacIntyre. “I've just had about four unlucky breaks, had to take a penalty shot out of a plugged lie in a bunker.
“Seventeen there, I just took one bounce and plugged on the bank of the bunker, couldn't move it forward, had to go sideways, made double. The scores are out there to get. Just disappointed with how it ended up.”
On a course he reckoned was in the top two in terms of the toughest he’s tackled in his career, MacIntyre only had two double-bogeys over the four rounds.
“Yeah, it is,” he replied to being asked if he felt that was one of the positives to come out of the week, “but that's two too many.
“I'm playing some great golf, and I'm livid right now with the way I finished. I was three-under par through three. I should never be shooting over par. I don't care what golf course I play on, it's not acceptable.”
MacIntyre now heads to Denmark and Germany for two European Tour events before heading back across the Atlantic for next month’s US Open at Torrey Pines in San Diego.
“All I want to do is go home right now,” he declared. “But we're going to Denmark after this. I've got to get my head around the disappointment, but that's golf. We take the good with the rough. This was a rough one, but we've just got to get on with it."
McIlroy closed with a 72 as he failed to break par during the course of the week at the venue where he won this event by eight shots in 2012.
“Yeah, more of the same, very average, sort of can’t really get anything going,” said the four-time major winner of his day’s work. “It was a day where you had to get off to a fast start, and I didn't do that and just sort of stuck in neutral.”
He said he “ didn't understand high expectations” of him coming into the week, even though he’d made a timely return to winning ways with a third success in the Wells Fargo Championship.
“It was good to get a win at Quail Hollow, a course that I've always played well on,” he said. “But I felt like coming in here there were still parts of my game that I needed to sharpen up, and obviously those parts were exposed this week in the wind and on a tough course.”