Some still stepped up to claim the biggest titles, however.
Jelena Ostapenko, unseeded and just 20 years old, went for broke repeatedly and won the French Open. Muguruza won Wimbledon in imperious fashion. Then Sloane Stephens, also unseeded, capped one of the most remarkable and expeditious comebacks from injury in tennis by winning the United States Open.
But nobody managed to be both consistently brilliant and consistently imposing, and while Pliskova and Halep both made it to No. 1, neither has won a Grand Slam title.
This has become a WTA hallmark.
Only two men have reached No. 1 in the ATP rankings without holding or having won a major singles title: Ivan Lendl in 1983, when the ranking system was based on an average of a player’s results, and Marcelo Rios in 1998, when, as in the present day, only certain results were counted.
Seven women have reached the top spot without winning a major, all since 2003, when Kim Clijsters became the first. The others: Amélie Mauresmo, Jelena Jankovic, Dinara Safina, Caroline Wozniacki, Pliskova and Halep. There could be one more after Singapore if Elina Svitolina, the Ukrainian currently ranked No. 4, gets back on a roll.
In the Slam-centric world of 21st-century professional tennis, this carries a stigma.
“I feel that winning a Grand Slam title is still the most important goal for players, more than becoming No. 1,” said Wim Fissette, who has coached Clijsters and Halep and just split with the British player Johanna Konta. “I’m sure Halep and Pliskova will feel a little more pressure now to win a Slam because they don’t want to be the player that was No. 1 but did not win a Grand Slam. But this pressure is created from the outside because I’m sure a lot of players would exchange careers with the unbelievable careers of Wozniacki or Safina.”
In statistical terms, it is actually tougher to reach No. 1 than to win a Grand Slam singles title. There have been 25 No. 1s since the WTA rankings began in November 1975. During that span, 43 different women have won major singles titles.
The same holds true for the men, where there have been 26 No. 1s but 48 different major winners since the ATP rankings began in August 1973.
“The No. 1 thing, no one can ever take it away from Simona,” said Darren Cahill, Halep’s current coach. “To some extent, I think it’s tougher to do: to be a great tennis player for 52 weeks of the year instead of getting hot for two weeks of the year. But we’re all about winning Grand Slams.”
There is of course no reason to blame Pliskova or Halep for reaching the pinnacle without ever winning a major, or in Halep’s extreme case for winning just one tournament of any sort in the last 52 weeks.
“The rankings don’t lie,” Cahill said.
The players know the rules and know the numbers, but it is fair to quibble with the ranking system. For now, winning a Grand Slam singles title is worth 2,000 points on the WTA Tour. Winning one of the four premier mandatory events is worth 1,000 points; winning one of the Premier 5 events is worth 900. Winning the WTA Finals with an undefeated record is worth 1,500.
Those numbers do not seem to reflect the relative value and impact of winning a Grand Slam title versus winning in Miami; Indian Wells, Calif.; Madrid; or Beijing (all premier mandatories) or in Singapore.
“I know that the mandatories are loaded with the top players and they are important, but for me a Grand Slam should be worth three of those,” Evert said. “There’s much more at stake. A Grand Slam should be at least 3,000 points.”
Such a change would indeed make it harder to reach No. 1 without a major (Halep has by far the best cumulative results of any player in the premier mandatories this season). But the WTA, which controls the ranking system, has no interest in diminishing the value of its own tournaments or in giving its players any further incentive to skip them.
In ranking terms, the majors have long been worth roughly double the tour’s top events, including 2002, the year before Clijsters broke the No. 1 mold.
What is intriguing is that the ATP follows the same approach and has produced so many fewer No. 1s without Grand Slam singles titles.
For the men, major titles are worth 2,000 points while winning one of the nine Masters Series events is worth 1,000 points. True, the ATP counts a player’s best 18 results, plus the World Tour Finals if he qualifies, while the WTA counts only a player’s best 16, plus the WTA Finals. But this, in theory, should make it slightly easier for a men’s player to fall short at the Grand Slam tournaments and still scale the top of the pyramid.
Instead, enduring champions like Roger Federer, Rafael Nadal, Novak Djokovic and Andy Murray have excelled on all fronts. Playing best-of-five sets at the Grand Slam tournaments could be a factor, reducing the possibilities of upsets. But the so-called Big Four — above all Federer, Nadal and Djokovic — have also hoarded the titles and ranking points at the best-of-three-set Masters Series events.
That explains why there are only four active ATP players who have been ranked No. 1 in singles while there are 10 active WTA players with that status: 11 if you count Martina Hingis, now a doubles specialist.
Five of those women are playing singles in Singapore, where the trophy is — like every trophy during Williams’s absence — very much up for grabs.
“We’ve had a very special era with Serena dominating and setting the higher standard, a higher level of professionalism and athleticism in tennis,” Evert said. “Serena’s just so comfortable with being No. 1. It’s normal for her. For these other players, it’s abnormal and it’s uncomfortable.
“I mean Serena’s probably watching this year unfold with one eyebrow up, thinking ‘Hmmm.’ ”