Despite recording a two-under par 69 during his second round, McIlroy’s progression up the leaderboard was badly hampered by closing with two bogeys, leaving the Northern Irishman sitting on one-over for the tournament. The world number two trails leader Jhonattan Vegas by a whopping nine shots and only just snuck into the weekend, finishing directly on the cut line as the likes of Shane Lowry, Jordan Spieth and Justin Thomas exited. Reports emerged at Quail Hollow on Friday that McIlroy’s TaylorMade driver – the same one he used to win the Masters – was deemed “non-conforming” earlier in the week after testing by the United States Golf Association (USGA). That meant McIlroy, who led the PGA Tour across multiple driving metrics heading into the PGA Championship after a stunning start to the year, was forced to switch to an alternative club prior to the competition getting underway. According to the tournament website, McIlroy has endured a 35.71% driving accuracy at the PGA Championship – he’s ranked T152nd in that category – and sits 35th when it comes to off the tee performance. "We have just became aware that Rory McIlroy’s driver, he was not able to use it this week,” said Taylor Zarzour of SiriusXMPGATOUR, who first reported the news. “It was deemed to be no longer permissible. "Whether it was cracked or something had happened to the head, Rory was unable to use the driver and switched drivers yesterday (Thursday). "He only hit four fairways yesterday and six today (Friday). SiriusXM reached out to the PGA of America and they chose not to comment. "The USGA conducted testing and when reached for comment they declined to comment, but did add that testing results are confidential, if the player wants to share they can, so maybe Rory will be asked.” McIlroy opted not to speak to the media after Friday’s second round so couldn’t offer any clarification on the issue, but Johnson Wagner insists the Holywood native is not at fault. "Drivers fail all the time, every single week somebody’s driver fails,” said Wagner of SiriusXMPGATOUR. “It’s no fault of the player, they don’t know how to do it. "It is a sophisticated testing system and when you’re a player like Rory McIlroy who hits the ball as hard as he does, the face naturally thins out, and when you’re hitting it like Rory McIlroy it thins out a little quicker. "It’s unfortunate it happened the week of a major and it might have cost him a few shots yesterday, but he seems to have it figured out and he did nothing wrong. "No player who fails a driver head test ever does anything wrong – this is something that happens week to week on the PGA Tour.”