The WTA Finals ended on an appropriate, if not entirely satisfying, note Sunday in Singapore. Pulled to her right by Angelique Kerber's so-so forehand, Dominika Cibulkova stepped over, adjusted to an extreme western grip and laid into a cross-court forehand. When the ball smacked the net tape, it had enough spin to crawl over and die on Kerber's side of the net.

Due largely to the mental yips, Cibulkova had failed to convert three previous match points. But serendipity earned her the fourth, and a 6-3, 6-4 upset of top-ranked Kerber in 1 hour, 16 minutes. It ended the official WTA tournament year on a surprising note.

"I have no words," the elated winner chirped in her on-court interview afterward.

She wasn't the only one.

Dominika Cilbulkova lost two matches in Singapore before rolling to the WTA Finals title. REUTERS

Kerber stood by, eyes glazed, through the trophy presentation. It seemed that her mind seemed a million miles away, which was not a bad place to go under the circumstances.

Granted, Cibulkova played exceptionally well in the final, while Kerber never got a handle on her game. On the other hand, it's fair to wonder what on earth Cibulkova was doing playing in the final. The details constitute a pretty strong case against the hybrid round-robin/knockout format, which will also be employed by the ATP in a few weeks at its own year-end shootout.

Let's set the table: Cibulkova, who will rise to No. 5 on Monday, is a useful player. A pugnacious, energetic, 27-year-old Slovak, she has been to the quarterfinals at every Grand Slam event. She has played in one major final, losing the 2014 Australian Open title match against Li Na. Cibulkova rode that achievement into the top 10 but soon after went into a terrible slump.

Consistency and loss of nerve have always been Cibulkova's bugaboos, and those are precisely the qualities that separate Grand Slam champions from the puzzling contenders and also-rans. You have to win seven consecutive matches over two weeks against a (presumably) escalating class of player to triumph at a major. It's a monumental ask.

Round-robin based events allow a player with a loss, or even two (as we've seen for the second year in a row in Singapore), to win the championship. Kerber's record in this week's WTA Finals was 4-1; Cibulkova finished 3-2, but she's the champ. It turns the most fundamental premise in tennis upside down.

You have to take a close look at Cibulkova's run to really appreciate all the irony in this scenario. Kerber bested Cibulkova in the first round-robin match for either player. Then Madison Keys crushed Cibulkova, giving up just five games. With the first two rounds of the round robin complete, winless Cibulkova's path to qualifying for the knockout stage was barely more than a mathematical oddity. She had to beat WTA No. 4 Simona Halep in straight sets and Kerber had to beat Keys in straights as well.

After Cibulkova did her part with a win against Halep, she wouldn't even watch or track the Kerber-Keys match on a live-scoring module. She went shopping and, as she told the press before the final, got the news that she had qualified when she returned to the hotel: "I started to get messages like, 'Congratulations, you are there!' We were just jumping and really, really happy."

Playing with house money against Kerber, Cibulkova hit the jackpot: She put 83 percent of her first serves into play, and her winners-to-unforced errors stats were nearly a reverse image of Kerber's. Cibulkova had 28 winners to 14 unforced, while Kerber had 14 and 23, respectively.

Furthermore, Cibulkova created an interesting template for how to play the top-ranked player. She served predominantly down the middle, keeping Kerber from taking charge with her return. When returning, Cibulkova went after Kerber's weakness, her second serve. Cibulkova played from on or inside the baseline, took time away from Kerber, found the angles and kept the ball deep. We'll see more women trying to implement those tactics come January.

It's no wonder Kerber looked so disenchanted after the match. When the players tell the media that they take all their rivals seriously, they're just reciting from the media-training handbook. A player who wins has every right not to want to go back out and play the person she has just defeated again, for even greater stakes.

"It wasn't easy, after two losses to play Halep," Cibulkova said. "First two matches I was a little unlucky. Today I was lucky."

It might have been the understatement of the week.