That quote also suprised me. I believe the Titleist Professional was a 1970s ball with a 1.62" diameter similar to the smaller British ball. I was really suprised at the current 1.67" diameter ball dimension, because that would seem to be either non-conforming or a mismeasurement due to the .168" miminum on diameter. Ifyou still have the article, which ball was quoted as having the 1.67" diameter?
BIG EDIT: The 12/28 edition of Golf World had this correction:
An editor's note in [Phil's 12/21 Q&A] stated we measured a Titleist ProV1x and a wound Titleist Professional. These measurements, however, were made by editors using calipers, which is not the method used for measuring by the USGA, nor is it exact, and the numbers published may have inadvertantly given the impression that these ball sis not meet the USGA standard for size. Both the Titleist ProV1x and, at its time, the Titleist Professional, fully conform to the Rules of Golf. Golf World regrets the error.