While Robinson's days as a ballplayer and pioneer have been well chronicled, his work as "an informal civil rights leader," -- a description given by his wife, Rachel -- has not been examined as deeply or as often.
In his book, Long unearthed never-before-published letters offering a rich portrait of the baseball star as a fearless advocate for racial justice at the highest level of American politics.
Long told the audience Thursday of Jackie Robinson's correspondence with such historical figures as Dwight Eisenhower, Richard Nixon, John F. Kennedy, Lyndon Johnson, Martin Luther King, Malcolm X, Hubert Humphrey, Nelson Rockefeller and Barry Goldwater.
"Jackie Robinson was more than just a baseball player," said Long, an assistant professor of religious studies at Elizabethtown College in Pennsylvania. "He was more than a Hall of Famer, and more than just the first African-American to shatter the color barrier in Major League Baseball.
"Most Americans, and especially white Americans, have not completely understood the real Jackie Robinson. And that's because we have frozen him in 1947. But, in reality, Jackie considered his life after baseball far more meaningful and far more significant than all of his exploits on the baseball diamond.
"And that said a heck of a lot for someone who stole home plate in the 1955 World Series."
The Padres recognized three local scholars of the Jackie Robinson Foundation and five from the Jackie Robinson Family YMCA in San Diego during pregame ceremonies before their 6-2 loss to the Atlanta Braves.
The Padres honor Robinson and his legacy with ongoing support of the Jackie Robinson Family YMCA.
After speaking at the Hall of Champions, Long joined broadcasters Dick Enberg and Tony Gwynn during the local broadcast of Thursday's game to share his research with viewers.
"Robinson's passion for civil rights was complicated and nuanced," Long said at the luncheon. "A natural maverick, he charted his own course, offering his support to Democrats and Republicans, questioning the tactics of civil rights leaders already in conflict with one another, and challenging the nation's leaders to fulfill the promises of democracy and capitalism."
Robinson's "maverick spirit" earned him enemies on both ends of the political spectrum, Long said. Malcolm X criticized him. The Nixon administration identified him as a threat significant enough to warrant a written report from FBI chief J. Edgar Hoover, Long said.
"These conversations reveal the scope and depth of Robinson's effort during the 1950s and 1960s to rid America of racism," said Long. "Writing eloquently and with evident passion, Robinson charted his own course, offering his support to Democrats and to Republicans, questioning the tactics of the civil rights movement, and challenging the nation's leaders when he felt they were guilty of hypocrisy -- or worse.
"Taken together, Robinson's letters and their replies provide us with new insight into the conversations that both created and weakened the civil rights movement.
"Above all else, however, these rich letters complete our picture of Jackie Robinson -- a Hall of Fame baseball player, to be sure, but also an extraordinary political powerhouse and a civil rights leader in his own right, who personified the first-class citizenship that he demanded for all Americans, and who, to the day of his death, fiercely competed for."