As the 2025 Masters tournament approaches, here’s a trivia question: Who owns Augusta National Golf Club’s course record? If you guessed Tiger Woods, Jack Nicklaus, or another illustrious name, you’d be wrong. But if you care about your money, you should care about the answer. Knowing it could help you immensely in investing. At Augusta, Jefferson “Jeff” Knox stands apart. Knox is an amateur golfer and an Augusta member with a virtuosic command over the course. In 2003, he set the course record of 61. Knox may also have held the best “job” in golf. Until 2023, he served as Augusta’s Masters “marker.” Augusta insists that no Masters competitor play alone, so the amateur marker pairs with a pro when an uneven number of golfers make the cut. Staying far from the limelight, Knox impressed countless better-known players as the marker, including 2017 Masters champion Sergio Garcia, whom he beat in 2006. Rory McIlroy, whom he beat in 2014, praised Knox’s putting in a 2016 issue of Golf magazine: “I’d take him over anyone in the world on those greens, hands down.” Knox’s Masters mastery turned on his impeccable short game — a bulwark against pros outdriving him by 50 yards. PGA Tour pro Kevin Kisner was quoted in that same issue of Golf magazine: “If the PGA Tour played every event at Augusta National, Jeff Knox would be on Tour. He doesn’t miss inside of eight feet.” Even Tiger Woods and Phil Mickelson sought out Knox’s putting advice before the Masters. A greater advantage, contributing to his putting prowess, was Knox’s course knowledge. Living 2.3 miles away, Knox played countless rounds at Augusta during his marker career. Conversely, pros making the cut play only around seven. “Local knowledge,” said McIlroy, was Knox’s most important asset. “He knows every blade of grass. That’s so key.” Ah, yes. Something had to give, right? A 50-something-year-old amateur who competed with — and sometimes bested — the world’s greatest players on a long, difficult golf course seems implausible. But Knox’s success is explainable: He is a testament to the success one can achieve, even against more skilled competitors, by building and focusing intensely within, what Warren Buffett once dubbed one’s “circle of competence.” The “circle of competence” is a simple idea. Many professionals hone outsized knowledge or skill through careful study or practice. Warren Buffett, who coined the term and introduced the concept in Berkshire Hathaway’s 1996 shareholder letter, built his circle of investing competence through obsessively reading annual reports and operating businesses — cornerstones of Buffett’s investing success. (Though operating within one’s circle of competence is not sufficient for preventing investing mistakes, as Buffett proved through blunders like U.S. Air and Dexter Shoe.) While Buffett can seem omniscient, he noted in that same shareholder letter that investors need only the “ability to correctly evaluate selected businesses.” He also stressed that, “You don’t have to be an expert on every company, or even many.” You can be extraordinarily effective within a narrow circle of competence as long as you stay inside of it, knowing your blind spots and understanding your limitations. Paraphrasing IBM founder Tom Watson, whom Buffett often quotes to explain the circle-of-competence concept, one needn’t be a universal genius to succeed in investing. Being smart in spots and staying around those spots is what counts. The “spot” Knox stayed around was Augusta. In the process, borrowing a line from comedian Bill Hader, he became the Daniel Day-Lewis of only doing one thing. His dedication to the course afforded him a competitive advantage against even the world’s greatest golfers. This success speaks to the extraordinary, playing-field-altering power of focus. And the spectacular results that Knox’s and Buffett’s circles of competence have produced are worth remembering in a world increasingly filled with technological distractions and fads to chase. Adam Philipp lives in Shaker Heights. The 2025 Masters at Augusta National in Georgia begins Thursday, April 10. Have something to say about this topic? * Send a letter to the editor, which will be considered for print publication. * Email general questions, comments or corrections regarding this opinion article to Elizabeth Sullivan, director of opinion, at esullivan@cleveland.com.