Trying to pick a winner at Royal Birkdale this week is as futile as counting grains of sand. The days when Woods could, like Roger Federer, be counted upon to pulverise his opponents by force of aura alone have passed.
Instead a legion of prospective successors are vying for prominence in the most even field in years. Rickie Fowler, Hideki Matsuyama and Justin Thomas are established stars, but they are all still queuing to join the major winners' enclosure.
Spieth argued that a palpable shift was taking place.
"It could be anybody this week," he said. "I don't know what's better for golf, but from my opinion, it's pretty exciting to beat this many players who have such confidence. Guys are learning, getting stronger.
"Over the next 15, 20 years, you will see a group of 10 to 12 guys having a lot of different competitions with each other as they come down the stretch. It's different from one person being the guy to beat."
The ever-ebullient Spieth was the future once. When, in 2015, he became the first since Woods to win the Masters and US Open back-to-back, Adam Scott labelled him the next Tiger. But ever since he hit two balls in Rae's Creek to toss away a four-stroke Masters lead last year, he has toiled to regain his lustre.
The notion that he, Day and Rory McIlroy could form a fearsome triumvirate lost currency fast. Dustin Johnson, blessed off the tee with the power of a lumberjack, pressed home his own credentials as the game's supreme force by winning three tournaments in a row, but he fell down the stairs of his rented home in Augusta and has not been the same since.
Golf is awash with the fearlessness of youth. Thomas Pieters, the stand-out performer of Europe's ill-starred Ryder Cup at Hazeltine with four points out of five, is a stripling at 24.
Tommy Fleetwood, the punkish local lad whose picture is pasted on every lamppost in Southport, is 26. Koepka, positively superannuated at 27, is another poster-boy for the next wave, having used his long hitting to win last month's US Open at Erin Hills by four shots. Even on the closing holes, as the size of the stakes dawned, he did not blink.
This is one of golf's greatest egalitarian stretches, which, come the end of the season, could match the record of nine consecutive first-time victories, starting with Graeme McDowell's at the US Open in 2010 and ending with Webb Simpson's at the Olympic Club two years later. So many of the fresh breed of champions grew up with aspirations of emulating Woods, to the point where none of them can accomplish his level of outright supremacy.
McIlroy, once breathlessly hyped as a talent capable of winning 20 majors, has missed four cuts just in the past six weeks.
Woods' otherworldly gift was not that he simply put together his annus mirabilis in 2000, with four straight majors to create the 'Tiger Slam', but that he sustained the same level for several more years.
Spieth, who conceded ruefully that he would always be held to the standard of 2015, could only marvel at the feat.
"Experiencing a year like that, it's just takes a lot out of you," he said. "It's very hard to do. You need a lot of things to go right at the right times."
The era of Woods was one of benevolent tyranny, where thousands would follow him for his pre-dawn Open practice rounds in anticipation of the crushing he would soon mete out.
Now, in his sorrowful absence, a major championship week derives its thrill from its sheer uncertainty, from the churning mix of players jostling to be next in line.
