When I met McIlroy, now the world’s No. 1 golfer, in New York in December, I asked him about the letter. “A lot of those memories have kind of blurred together,” he said somewhat sheepishly. “But, yeah, it went something like that.”

McIlroy’s “Tiger letter” most likely never got to its intended addressee, but by now its message surely has. McIlroy has already won the U.S. Open, the British Open and two P.G.A. Championships, becoming just the third golfer, after Jack Nicklaus and Tiger Woods, to win four majors by the age of 25. The only major he hasn’t won is the Masters, which starts April 9 in Augusta, Ga. A victory there would give him a career grand slam — a feat accomplished by only five other golfers, and by only one younger than McIlroy: Woods.

The matchup in Augusta between the former and current world No. 1’s will most likely not come to pass, with Woods sidelined by a balky back. It is uncertain whether Woods will ever regain a semblance of his former mastery, just as it is unknown whether McIlroy, or anybody, could ever be the next Tiger Woods. Woods hasn’t notched a victory in 20 months, yet he has still won an astounding 26 percent of the tournaments he has entered (Jack Nicklaus, an 18-time major winner, won 12.7 percent). Woods has also played an unparalleled part in elevating pro golf to a multibillion-dollar-a-year industry and spawned a new global generation of superb golf athletes, making it all the more unlikely such a transcendent figure could ever emerge again. All of which makes McIlroy’s rise to the top of his sport that much more intriguing.

Rory McIlroy “could turn out to be the best player in the world in his time,” Gary Player, a nine-time major winner, said in 2009 after McIlroy closed out his first Masters appearance at age 19 with six birdies and four pars on his last 10 holes. “This young man is brilliant,” Player said. “His theory side, his swing, is better than Tiger Woods’s.” Before McIlroy’s U.S. Open victory in 2011 at Congressional Country Club in Bethesda, Md., Ernie Els proclaimed him good enough to “change golf history.”

Comparisons with the likes of Nicklaus and Woods seem at best woefully premature, even when they come from the two golf legends themselves. In the wake of that same 2011 U.S. Open, Woods acknowledged that McIlroy, then 22, had a better swing than he did at that age. Nicklaus capped off McIlroy’s fourth major, last year’s P.G.A. Championship at Valhalla in Louisville, Ky., by proclaiming, “Rory has an opportunity to win 15 or 20 majors or whatever he wants to do.” And yet in a mind-bendingly precise and difficult sport like golf, there are qualities and essences, far more subtle and, in the end, more substantive than mere victory totals, that define greatness.

Pro golf is in many ways better viewed today on TV than on the course. With sophisticated camera work, computer simulation, slow-motion-swing and shot-tracer technology, TV viewers are able to engage in the physical arc of individual shots and to appreciate what finely tuned outdoor pool sharks pro golfers essentially are, playing the angles, cushions and caroms of vast, undulant tables with 18 ever-shifting and often sinisterly sequestered pockets. We duffers wield the most forgiving grade of clubs, designed to tolerate and adjust for our errant strikes. Pros play blades, clubs with smaller and yet more powerful sweet spots, their double-edged dynamism yielding both greater rewards and greater rebukes.