Tavis Smiley’s departure from National Public Radio will be a loss not only to blacks but also to all NPR listeners.

For its part, NPR issued a vague statement that is long on happy talk about Smiley helping to “jump start” its effort at reaching blacks.

Smiley’s departing letter to local stations asserts that NPR has “failed to meaningfully reach out to a broad spectrum of Americans who would benefit from public radio.”

Smiley may simply have been tired of banging his head against the racial wall. He told me when I interviewed him a year ago that he was often frustrated and exhausted from doing the work involved in putting together a meaningful show five times a week, while at the same time tussling frequently with NPR over the show’s tone and guests.

“The most difficult thing that I have had to do,” he told me, “is fight a culture at NPR, a culture that is antithetical to the best interests of people of color.”

The African American Public Radio Consortium, which helped recruit Smiley four years ago, has meanwhile urged Smiley’s listeners to stay with NPR. Perhaps they will, as NPR embarks on a search for a new permanent host to replace Smiley.

But Smiley is a personality with particular cachet among many blacks. He has a fan base that has followed him from his days on Black Entertainment Television to “The Tom Joyner Morning Show” on black commercial radio.

And there is a strong possibility that the many ears of color that Smiley brought to NPR will not find enough to keep their attention once he leaves.

Therein lies a fundamental problem with NPR’s approach to diversity: One show cannot carry the burden of overcoming a longstanding culture that failed to reach people of color.

NPR research shows “The Tavis Smiley Show” to have a listenership that is 29 percent black and 40 percent under the age of 44. Each measure is the highest of any NPR program, making the show’s audience among the most diverse in public radio.

In addition, NPR asked Smiley to work this particular miracle and then proceeded to question the way he did it. “The struggle that I am engaged in, and that my staff is engaged in, is to get this network to understand that we live in the most multicultural, multiracial and multiethnic America ever, and that we know how to do this show,” he told me.

During Smiley’s time at NPR, the network and its stations reportedly questioned his openness with his liberal political views, his irreverent style and his willingness to ask challenging questions, as well as to allow a few arguments to break out on his show.

Stations were concerned about Smiley’s boisterous and casual speaking style, widely recognized in black America but different from the conversational tone and ethnically neutral inflections of many NPR hosts.

NPR wanted to bring about racial diversity in public radio but to somehow do it in a way that didn’t disturb its status quo.

Unfortunately, the ironic result is that the network now faces the embarrassing loss of a key player in its dream of a more multicultural NPR. This may cost it some goodwill, especially among the listeners of color that it wanted so much to attract.