CINCINNATI -- It is fine for baseball to celebrate its history, its place in civil rights history, its best and brightest moment formed by the appearance of Jackie Robinson in a Major League uniform on April 15, 1947.

But the celebration should not be allowed to overshadow the other side of the equation. On a percentage basis, the number of African-Americans playing in the Major Leagues is little more than one-third of what it was at its peak 35 years ago.

What baseball does not need at this juncture in its history, and in American history, is to resemble the Boston Red Sox of the pre-Pumpsie Green era.

The apologists will point out that the game is actually more of a melting pot than it was 35 years ago, that it has more of an international flavor than it ever did. And it is true that the semi-disappearing African-American ballplayer has not been replaced statistically by a garden-variety Caucasian. An influx of Latin American players, and more recently, East Asian players, has not only diversified the game, but has given it a deeper, wider pool of talent.

But this is not about that. The legacy of Jackie Robinson is what sets this game apart from not only other sports, but from plenty of other social institutions that were white-only in 1947 and well beyond. There will be no reason for rejoicing when the number of Outer Mongolians in the Majors exceeds the number of African-Americans.

What happened here? What happened to the wonderful, singular momentum generated by Jackie Robinson? Why has his history-making legacy been allowed to shrink before our very eyes? Thousands upon thousands of words have been written on this topic. After you have read much of the literature, you come to this unavoidable conclusion: Nobody really knows why.

This question arose at a media session at Great American Ball Park on Saturday night, just before the Civil Rights Game between the Chicago White Sox and the Cincinnati Reds. Two legends of the game, two members of the pioneering generation of African-American players, Henry Aaron and Frank Robinson, were asked this very question: What has happened to baseball in the African-American community?

"You can't find one person who can tell you that," Robinson said sharply. This is probably the single best answer the question can provoke.

Aaron's answer was more expansive and made sense as far as it went. He said that baseball required more equipment and more expense than, for instance, basketball. Plus, there was the matter of something resembling a full-fledged field required for a game. He said that in his hometown of Mobile, Ala., he noticed that the playing fields of his youth no longer existed.

"You can't play on that field anymore," Aaron said. "It was a cow pasture. Now, it's housing. Basketball is a different story. You can put up a hoop in this [interview] room and play basketball."

That's a nice, tangible answer, although it might not explain the entire phenomenon. Thirty-five years ago, 27 percent of all Major Leaguers were black. That number decreased until it reached a low of just over eight percent in 2007. That 27 percent figure is now occupied by Latin American players.

Robinson pointed out that this season, the percentage of African-American players increased for the first time since 1995, to just over 10 percent. If baseball is fortunate, this is a trend. If baseball is unfortunate, this is an aberration.

Major League Baseball has made serious attempts to reverse the erosion of its base of African-American players. Inner-city baseball academies have been created. There has been the RBI (Reviving Baseball in Inner Cities) program. This is all well-intended stuff and it beats passively losing an entire portion of the population. But it is too soon to know about the long-range consequences.

One thing is certain: Many of the people who attempt to explain the decrease in black baseball players by making generalizations about African-American culture are generally annoying at best and completely wrong at worst. This is because so many of them are white. They tend to live in distant exurbs and have absolutely no idea what they are talking about.

The progress that baseball has made in the area of diversity was evident in the two teams in the 2009 Civil Rights Game. The White Sox won a World Series championship with their current manager and general manager, Ozzie Guillen, a Venezuelan, and Ken Williams, an African-American. The young and promising Cincinnati team is led by one of the most respected managers in the game, Dusty Baker, an African-American. These two teams are ideal participants in the Civil Rights Game.

But this is no time for baseball to become smug or complacent. One major difference between 1947 and now is that when Jackie Robinson arrived with the Brooklyn Dodgers, baseball dominated the American professional sports landscape. Professional basketball was in its embryonic stage. Professional football was less popular than college football. The National Hockey League had six teams. Baseball's cultural reach was unmatched.

Today, the marketplace is much more competitive, not only for fans or listeners or viewers or readers, but for athletes. As Commissioner of Baseball Bud Selig often says, Jackie Robinson breaking the race barrier was "baseball's proudest moment and its most important moment."

There is no dispute about that. It was an important moment, not only for baseball, but for all of American society. But it is also a 62-year-old moment. At this moment, what counts as much is what baseball will do next in America's inner cities. It has a civil rights legacy worth preserving, but that legacy doesn't live on without a continuous, working commitment.