In some years, the players of the year are those who clearly dominated the playing field. Think Roger Federer in 2006, Novak Djokovic in 2011, or Serena Williams almost any time (on the Mayan as well as Gregorian calendars).

This year, my choices for player of the year won but one Grand Slam title between them. And just one finished the year ranked No. 1 -- and that just by the skin of her teeth.

I’m guessing you know my WTA pick: Serena Williams. On the men’s side, my POY is Kei Nishikori.

First, let’s clear up any confusion about what qualifies a player for my award. You can’t play like dog poop and earn the distinction, but piling up the W's doesn’t get you the nomination, either. To me, the POY is the male or female who had the greatest impact on the game. Often, that’s also the best player, as in the case of Williams in 2014.

Sometimes the POY is the athlete who brought more than just a walloping serve or ball-crushing forehand to the party. It’s the player who captured our collective imagination, elevated the game in the public eye, or achieved something few had anticipated and surprised us. And that’s what Nishikori did this year.

Serena is one of the biggest tennis personalities ever to pull on faux biker boots. But most years she’s been so deadly efficient on the court that she was a strong candidate for POY based exclusively on her record. This year, it was different. This year, we weren’t asking, “Can Serena achieve a Grand Slam?” or “Will she lose a set during the tournament?”

Instead, for most of the year we were asking, “What’s wrong with Serena?” And let’s be frank here: By August, many wondered if she was through winning majors.

This situation caused endless anxiety for Williams fans, but it helped the game. And it provided a nice counterweight to one of the other big WTA stories of the year, the breakthrough by Eugenie Bouchard. For the media, Williams is the gift that just keeps giving. And she’s such a great player that she’s an even bigger story when she’s losing than when she’s winning.

Williams kept us on tenterhooks for most of the year. She lost in the fourth round of the Australian Open to Ana Ivanovic (who had never previously beaten Williams). She then suffered the worst defeat of her Grand Slam career when Garbine Muguruza allowed Williams just four games in a second-round clash at the French Open. At Wimbledon, she lost to Alize Cornet in singles and then withdrew (with partner and sister, Venus) a few games into a doubles match due to a disturbing episode of physical disorientation.

The story of Williams’s demise was all teed up for the U.S. Open. But after Wimbledon, Williams proceeded to win 19 of her last 20 matches of 2014, including a dramatic and entertaining U.S. Open final. She had kept us on the edge of our seats all year, and then turned a potentially sad story into a glorious one.

There’s also this: When it comes to the WTA, Williams remains the only fixed point on an ever-shifting and confusing plain. It makes you wonder what will happen when she’s gone.

If you wanted to nominate an "anti-Serena" in the personality department, Nishikori would surely be on your short list. The 24-year old Japanese isn't so much self-effacing as he is introverted. Nishikori is so absorbed in the day-to-day demands of his profession that he has almost no media presence. His game is equally understated, which is one of the reasons so many fans, upon seeing him in the U.S. Open final, wondered how he got there.

Well, the answer is fairly simple: He’s a wonderful ball striker with clean, grooved strokes. He’s remarkably nimble and willing to take the ball on the rise. Also, he has a grinder’s mentality. He can simply outlast run-of-the-mill opponents with his superior consistency and patience, and keep pace with the elite players because his focus keeps at bay some of the customary fears and doubts attendant to facing a Djokovic or Federer.

That alone wouldn’t necessarily net him distinction as the ATP POY. After all, Marin Cilic was an equally surprising U.S. Open finalist, and he beat Nishikori for the title. Another introvert, the 26-year-old Cilic has two years on Nishikori, but has won just three of their eight meetings (including 1-2 in 2014). At 6-foot-6, Cilic is another in a long line of sinewy, towering Croatians who have left their mark on the game.

By contrast, Nishikori is a mere 5-foot-10. In baggy shorts and a baseball cap, he looks as if he just wandered in from a panel in "Peanuts." He’s one of the players who seem designed to demonstrate that, contrary to popular belief (and the existence of thumpers like Cilic) that "bigger" doesn't necessarily translate into "better." Thanks to guys like Nishikori, slightly built men and women know there’s always hope.

Nishikori, who finished the year at No. 5, also established new high-water marks for Asian male players, a valuable service at a time when the game is enjoying a growth spurt throughout the Pacific region. To be sure, tennis is no novelty in Japan, nor will the Chinese fall all over themselves to embrace Nishikori as some sort of pan-Asian hero. But it was high time for an Asian man to step up and serve as a convincing regional role model.

This was a somewhat odd year in pro tennis, as presaged at the Australian Open by that Ivanovic upset of Serena and the muted men’s final that produced a 29-year-old first-time Grand Slam champion, Stan Wawrinka.

And, in some ways, the Grand Slam cycle ended with equally big surprises thanks to players of the year Serena Williams and Kei Nishikori.