The news of Rory McIlroy’s driver being ruled nonconforming for exceeding the spring-like effect prior to the start of this week’s PGA Championship has spread like wildfire since first being reported Friday afternoon. So have the questions. Many can be answered, and while some of those answers might be incomplete—in that they rest entirely within the workings of McIlroy and his camp—most are pretty clear. Here’s a quick look at the most pertinent issues regarding the way drivers are tested and what is and isn’t cheating.
So Rory was using a hot driver, basically cheating, right?
No. This is not a corked-bat situation. While we don’t know all the ins and outs of McIlroy’s specific test with his TaylorMade Qi10 driver because under the process for testing drivers for CT (characteristic time) that is employed at PGA Tour events and major championships, test results are held in confidence, aside from pulling the driver from competition.
What is that test like?
The CT test is a sophisticated but quick field test to determine if a driver’s face is too springy. It uses a scale of microseconds to determine face flexibility where the legal limit is 239 with an 18 microsecond tolerance to make the overall drop-dead limit of 257 microseconds. This is basically like the idea of having a speed limit of 65, but knowing that you’re only getting pulled over if you’re running at 72. However, unlike the speed limit example, the difference between 239 and 257 is simply the tolerance of the measurement device. The difference in performance between something a little under the limit and something a little over the limit would likely be the difference in two drives measured in feet, not yards.
A picture of the USGA's CT testing machine.
USGA staffer Jacob Spurgeon uses the CT testing equipment at the USGA Testing Facility in Pinehurst, N.C.
Jonathan Kolbe
Doesn’t everybody get their driver tested every week?
Routinely, drivers are tested during the year at PGA Tour events and some major championships in a randomized fashion to determine whether a driver is close to or over the limit. Maybe a third of the field might get called in on a particular week, and in addition at some tour events the USGA might test extra driver heads that are in the tour equipment vans to prevent any problems.
At the PGA Championship, the test was conducted at the request of the PGA of America, and the PGA controlled the dissemination of the results to players and the media. It is our understanding that drivers from many manufacturers were tested this week, and other players besides McIlroy might have failed the test, but we cannot confirm this information. The PGA of America declined to comment on the results this week, but did release the following statement:
“We can confirm that the USGA was invited to do club testing at the PGA Championship, at the PGA of America’s request. That testing program is consistent with the same level of support that the USGA provides to the PGA Tour and other championships, as part of their regular programs for driver testing. The standard process is for about a third of the field to be randomly tested under the program. That was the case at Quail Hollow this week. Finding driver heads that have crept over the line of conformance is not an unusual occurrence, especially for clubs that are hit thousands of times over a long period of time. The results are kept confidential to protect players, who are unaware the club has fallen out of conformance and not responsible for it falling out of conformance other than hitting the club thousands of times. Players are simply asked to change heads if necessary, and all do without issue. To publicly identify players whose club did not conform can lead to that player being questioned unnecessarily. Neither the USGA nor the PGA of America have any concerns about player intent.”
Wouldn’t Rory want to know where his driver stands all the time?
Yes. Those tests also are often done by manufacturers at their R&D headquarters, or a player could have his driver tested at equipment company trailers found at tour events during the year. However, those machines all have variances just like the scale you have in your bathroom compared to the one at the doctor’s office. There are ways to calibrate the hundreds of CT machines in the field with the one used by the USGA, but it is still a possibility that one CT machine in the field might yield a different result, one that is off a few points. In short, that means a player could think his driver was conforming but then when it’s officially tested it might just be over the limit.
Jared C. Tilton
So again, why doesn’t every driver get tested every week?
While the test is relatively quick, there usually is only one technician doing testing at an event at a time. With 156 players getting their drivers tested, that would be a practical impossibility. That said, if there was a commitment to have the driver testing process made mandatory, it could be done.
Was Rory’s driver always hot?
Very, very, very unlikely. Two things to be aware of: First, manufacturers aren’t giving their players hot drivers. It’s not a good look and as we’ve said above the advantage for being just over the limit isn’t all that tangible. Also, the springier a driver face gets, the quicker it is not just to fail but produce squirrelly shots because it can deflect at impact in a way that produces wayward misses. Second, there is a major glitch in drivers today called CT creep, which Haigh alluded to in his statement.
That sounds spooky. What is it?
It is spooky. The USGA and R&A have been studying this characteristic for the last several years because it basically means that a driver that was conforming in the past would become nonconforming after lots and lots of hits from players with very high swing speeds (most tour players, basically).
Is this what happened to Rory’s driver?
Again, we don’t know because the policy for the on-site testing of drivers at tour events and majors is to not release any information publicly. (Personally, that’s a bad policy because it creates confusion and speculation. It is not a stretch to say that McIlroy’s driver was not the only one ruled non-conforming this week or this year, but we don’t hear about this because it isn’t made public.)
All of that said, let’s look at what we know about McIlroy’s case. He was using last year’s TaylorMade Qi10 driver, a driver he clearly loved because after switching to the new Qi35 model for three rounds at the Arnold Palmer Invitational in March, he spent $995 on an Uber driver to deliver the Qi10 driver from his home South Florida to Orlando for the final round. Presumably, his Qi10 has a lot of miles on it.
A lot of hits on a driver that was measured initially somewhere in or around the tolerance zone of the CT test could creep into the danger zone. That effect obviously could have happened over time, and we don’t know the last time McIlroy had that model tested, either by TaylorMade or officially at an event, but he would have had no reason to give it up. The way CT creep works, we think (because it’s still being researched) his driver could have been under the limit at the end of play at last week’s Truist Championship and over the limit after hitting 50 drives during Tuesday’s warmups.
OK, we get that his gamer broke the rules. Why wouldn’t he just have a bunch of backups ready to go?
Maybe this is a dirty little secret, maybe it isn’t, but drivers are not like baseball bats or iPhones. They are all a little bit different, especially in the hands of an elite virtuoso. They are more like guitars or pianos. So while the exterior might look the same and the centers of gravity might be fairly close and the general spring-like effect could be the same, the subtleties are instantly detectable by someone like Rory. There’s a reason he plays the specific club he plays. That trend has been true among elite golfers since the days of Bobby Jones, whose clubfitter once had to work through thousands of hickory shafts to find one to match that in his favorite driver. In other words, McIlroy’s Qi10 this week is the same model as he’s been playing. It is not the same driver. And that could explain why his driving suffered so much. Was he hitting it 20 yards shorter this week compared to last week because he’s now playing a driver with a face that conforms to the rules? Or because he was using a driver he knew wasn’t his favorite? Perhaps only he knows. But because of what the CT test is, how it’s done, how subtle it is and what it means, maybe he doesn’t know, either.