The Northern Irishman and four-time major winner bogeyed the last at Baltusrol Golf Club in New Jersey to card a respectable one-under-par 69 Friday.
Yet with the cut beginning at the three-over-par mark, that wasn’t enough to dig McIlroy out of Thursday’s four-over-par round of 74.
“Tee to green was good,” McIlroy said of his week’s work. “But it was just pathetic when I got onto the green.”
“If you had to given anyone else in this field my tee shots this week, they would have been up near the top of the leaderboard. It just shows you how bad I was around the greens,” he said.
Four-time major winner McIlroy has only one tournament victory to his name in 2016. And he went on to describe his form over the past year as “disappointing” by his own exacting standards.
“It’s really disheartening,” McIlroy continued, “I need to go back to the drawing board and see where we go from here.”
There were no such existential troubles for McIlroy’s playing partner and reigning PGA champion, Jason Day.
The world No. 1 landed five birdies on the back nine to finish on seven-under-par, two shots back on joint leaders Robert Streb and Jimmy Walker.
Streb carded a remarkable seven-under-par 63 Friday but only a bogey from Walker at the last ensured there would be a tie atop the leaderboard going into Saturday’s third round.
With only 28 players having ever carded a 63 in major tournaments, Streb was unsurprisingly excited when speaking to the media later.
“I was waiting on it to break, waiting on it to break,” he said of the final putt of his round on the ninth hole that secured his score.
“Finally, (it) turned there at the end. But it was a great round. Happy to be a part of that 63 club.”
The 29-year-old American, who has just one career win to his name, will now look to fend off the likes of Walker, Day and Argentina’s Emiliano Grillo who recorded a solid four-under-par 66 Friday to tie for third position.
Recently crowned British Open champion, Henrik Stenson is also in the hunt for back-to-back majors on six-under-par.
At three-under-par, the likes of Jordan Spieth, Zach Johnson and Adam Scott remain in contention.
Elsewhere Friday, US Open champion Dustin Johnson saw no turnaround in fortunes as he carded a two-over-par 72, leaving him nine-over-par for the week.
Big hitters Sergio Garcia, Shane Lowry and Graeme McDowell also all missed the cut.