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.