To say that these are unprecedented, soul-searching times for American tennis is no exaggeration. If not for a pair of sisters — Serena and Venus Williams — the United States would be zero for the past 11 years in Grand Slam singles titles.

To put that in perspective, since the late 1800s to early 1900s when the four Grand Slam tournaments began, America has never gone more than a handful of years without garnering a major singles title. In fact, the United States is the most dominant nation in Grand Slam history with 314 titles compared to 135 for second-place Australia.

In the third-most-populous nation, full of resources and opportunities, the question begs to be asked: What has led to the American Grand Slam champion suddenly becoming an endangered species?

The scarcity has endured for so long that one writer dismissed all the consternation with new-world-order sentiments: "Tennis loves to play up nationalism — look at a scoreboard or draw sheet, and you'll see a flag or country abbreviation next to a player's name. But it's an individual sport, and players play first and foremost for themselves."

In other words, Americans shouldn't care if Americans don't win majors anymore.

This notion, that "tennis loves to play up nationalism" is a little like saying "the Olympics likes to pit one country against another." Um, that is called reality. Most of us bear loyalty to our country of birth or residence — even with its imperfections — and take pride in seeing one of our own succeed.

Would someone in Spain care as much about Rafael Nadal if he were from, say, Finland? You know the answer. Heart is where the home is … or something like that.

That little rant aside, there are plenty of theories as to why America is no longer producing major singles champions.

There's the Leftover Theory, which posits that the "big five" — football, baseball, basketball, hockey and soccer — attract the best young athletes, leaving tennis to dumpster-dive for scraps.

There's the Big Government Theory, that the United States Tennis Association needs to spend much more than the $17 million it annually pours into its centrally managed player-development system.

There's the Hunger Theory, which snivels that American players are too coddled (as a result of USTA Big Government) in comparison to their counterparts in poorer countries whose desperate circumstances lead to a desperate drive to be the best.

I'll leave the debating of theories to others, but I will say this: Every Grand Slam champion I've observed has had a special coach or mentor or parent who possessed the know-how to take his or her charge from good to great. Richard Williams, in navigating his daughters from the public courts of Compton, Calif., to the stadium court of the U.S. Open, obviously had the gift.

The same can be said for Toni Nadal, the uncle and lifelong pedagogue of defending champion Nadal. Toni's influence on Nadal has been immeasurable, but he couldn't keep his nephew from hurting his wrist in training earlier this summer, causing the world No. 2 to pull out of the year's final major.

But don't assume that the previous holders — Andy Murray and Novak Djokovic — are the de-facto favorites. Since Ivan Lendl departed as Murray's coach, Murray has slipped from being a perennial top-four member to No. 9 in the rankings. And while Djokovic's Wimbledon title may have portended that he was back to his major-winning ways, his recent marriage and upcoming baby carriage are being whispered as reasons for his less-than-stellar hard-court season leading up to the Open.

With only three American men ranked in the top 50, big-serving John Isner, currently No. 15, is the best hope to break the U.S. men's major drought. But even with Nadal out and Djokovic and Murray struggling to find form, Isner still would have to contend with such rising stars as (and pardon for mentioning their countries) Canadian Milos Raonic and Bulgarian Grigor Dimitrov (both Wimbledon semifinalists), France's Jo-Wilfried Tsonga (Toronto winner), and last but certainly not least, Swiss Roger Federer, the five-time Open champion who enters New York with a hot hand after winning Cincinnati and reaching the final in Toronto.

There is more promise for an American winner on the women's side. Serena Williams, going for a three-peat, also won Cincinnati and seems to be heading in the right direction after poor results in this year's other majors. No. 22-ranked Sloane Stephens and No. 28 Madison Keys are two up-and-comers.

And that's exactly what American fans will do for the next fortnight in Flushing — tune in to watch. But at some point, it would be nice — at least for us flag-wavers — to see more of our own actually win.

David Wheaton reached the quarterfinals of the U.S. Open in 1990. His new book, "My Boy, Ben" — about a yellow Labrador he had during his tennis-playing days — releases Oct. 15. Find out more at davidwheaton.com