McIlroy was only six shots off the lead after Thursday’s opening round but now sits in a tie for 35th place, well adrift of US pacesetters Max Homa, Scottie Scheffler and Bryson DeChambeau.
Bogeys at five and seven for the Northern Irishman were followed by a damaging double bogey at the 11th when he found the water.
“Tough day, really tough day. Hard to make a score and just trying to make as many pars as possible,” McIlroy reflected.
“I felt like I did ok. I made bogey on 14 and just to par the last four holes and get in the clubhouse and have a tee time tomorrow [Saturday[, I’m pretty happy with that.
“Scoring was very difficult. Just one of those days. Most of the field couldn’t get anything going so it was just a matter of trying to hang in there as best you could.
“Mentally it’s a grind. You just have to commit as best you can to the shot you’re trying to play and hit at the right time as well, pretty tricky.
McIlroy’s group were among the later starters on day two and their round lasted six hours and two minutes.
“It felt long. My golf swing felt horrific for the last six or seven holes just from waiting around, especially the 11th hole. It felt like that took about an hour to play.
“It was stop and start. Hard to get into a rhythm with the conditions and obviously how slow the play was as well.”