Too early to write off Serena Williams

— -- For years, when she seemed more interested in the thrilling concept of being Serena Williams, many thought she didn't care enough about tennis.

Now, after the news early Thursday that she is done for the 2015 season, there is evidence that six days into her 34th year, perhaps she cares too much.

With a shattering loss to Italy's  Roberta Vinci in the semifinals of the US Open in September, Williams saw her breathtaking run at a calendar-year Grand Slam end abruptly. It also ended a ridiculous run of 33 straight major singles victories.

She acknowledged the decision on the China Open website.

"It's no secret I've played injured most of the year," Williams was quoted as saying, "whether it was my elbow, my knee, or, in the final moments of a certain match in Flushing, my heart."

Dramatic, of course, but true, too.

Indeed, Williams was a broken spirit after losing to Vinci in three sets. One of the truisms on today's WTA Tour is that only Serena can beat Serena. It was never truer than against Vinci, whose set wins were the first of her career against the No. 1-ranked American.

Williams had won four consecutive Grand Slam singles titles -- twice -- but never in the same season. In 2002-03, she captured the "Serena Slam," but fell to Justine Henin in the semifinals at the French Open. Williams arrived in New York this year with a chance to become the first player, man or woman, to sweep the season's majors since Steffi Graf did it in 1988. The media attention was intense. And while Williams repeatedly insisted she didn't feel any pressure, her actions on the court -- and later, the comments of her mother, Oracene, and coach, Patrick Mouratoglou, suggested otherwise.

Her postmatch news conference was uncharacteristically brusque and brief. There were only 12 questions before she excused herself, and several answers were of one or two words.

"I don't want to talk about how disappointing it is for me," Williams said after the first question. "If you have any other questions, I'm open for that."

And so, she'll be missing in action from the China Open that begins Saturday in Beijing, as well as the year-end championships in Singapore. It's a huge loss for women's tennis.

Now that it's over, let's try and place her magnificent season into the context of the great ones.

Williams' sporty 53-3 (.946) record is the 12th-best, percentage-wise, of all time -- behind Martina Navratilova's 86-1 (.989) in 1983 and some distance behind her own best in 2013 (78-4, .951).

In terms of majors, Margaret Smith Court's 1970 season and Graf's 1988 campaign are the only calendar-year Grand Slam runs in modern women's tennis history. Court, incredibly, won three of four majors on four other occasions. Graf accomplished it three more times and Navratilova twice.

Williams, who has amassed 21 Grand Slam singles titles, will have her chance to catch the only two women ahead of her -- first Graf, with 22, and Court, with 24.

It could happen in 2016 -- but will it?

The fascinating question will be how Williams reacts to what may be the greatest disappointment of her career.

For many athletes on the precipice of history, this would be a career-breaker. For others --  New England Patriots quarterback Tom Brady comes to mind -- adversity is what feeds the fire.

Williams has a sturdy history of responding well to injuries and health scares. If she has difficulty finding motivation, as many aging athletes do in their advancing years, this immense loss could be the chip on the shoulder that drives her into unprecedented territory.