A baseball historian and author, Ralph Wimbish, remembers how a great Black ballplayer, Buck O’Neil, laughed at the thought of Major League Baseball blending statistics with the Negro Leagues.

The all-time great “would get a good chuckle when I said we ought to bring back the Negro Leagues and include the Major League stats in there,” Mr. Wimbish told the Sun. “I guess they’ve finally done the reverse after all this time, which is good.”

O’Neil, a first baseman and manager, mostly with the Kansas City Monarchs, is among more than 2,300 Negro League players whose statistics from between 1920 and 1948 are now added to the MLB record books. Major League Baseball announced that the inclusion took effect on Wednesday, creating new leaders atop some of the sport’s most cherished categories.

A Negro Leagues legend and Baseball Hall of Famer, Josh Gibson, becomes the all-time leader in batting average (.372, passing Ty Cobb), slugging percentage (.718, passing Babe Ruth), and OPS (1.177, passing Ruth again). Gibson also owns the records for single-season batting average at .446, single-season slugging percentage at. 974, and single-season OPS at 1.474.

A catcher, Gibson played 17 years with the Homestead Grays and Pittsburgh Crawfords and died at age 35, three months before Jackie Robinson broke Major League Baseball’s color barrier in 1947. That ultimately led to the demise of the Negro Leagues.

A journalist and author of a new book, “Larry Doby in Black and White: The Story of a Baseball Pioneer,” Jerry Izenberg, said the updated statistics add credence to the legacy of the Negro Leagues. “Nobody can deny Josh Gibson, but numbers did deny him until now,” Mr. Izenberg told the Sun. “He was a fabulous, fabulous player.”

The Negro Leagues Statistical Review Committee, which included historians, former players, and researchers, sifted through box scores, historical data, and other resources for relevant statistics and information. Recordkeeping could be spotty, and Negro League players labored under difficult conditions. There were anywhere from 60 to 80 games in a Negro League season. Statistics from exhibition or “barnstorming” games were not counted.

The MLB commissioner, Rob Manfred, said in a statement, “We are proud that the official historical record now includes the players of the Negro Leagues.“ His initiative is focused on ensuring that future generations of fans have access to the statistics and milestones of all those who made the Negro Leagues possible. 

Mr. Manfred adds that “their accomplishments on the field will be a gateway to broader learning about this triumph in American history and the path that led to Jackie Robinson’s 1947 Dodger debut.”

The statistics of one-time Negro League players like Robinson, Willie Mays, and Doby are updated to include 10 more hits for Mr. Mays and 49 more for Robinson. The pitcher Satchel Paige had 28 Negro Leagues victories added to raise his win total to 125.

“Thanks to MLB Commissioner Rob Manfred for his embracing of the importance of the Negro Leagues and an incredible team of historians and researchers who have dedicated themselves to pull this groundbreaking data together,” the president of the Negro Leagues Baseball Museum, Bob Kendrick, said in a statement. “This is a major milestone in baseball history.”

The Special Baseball Records Committee of 1969 voted to include statistics from  the American League, National League, American Association, Union Association, Federal League, and Players’ League but failed to give the Negro Leagues Major League status until 2020, when the Negro Leagues Statistical Review Committee began its work.

All statistics will be updated as new data and relevant information is discovered. MLB clarified that none of the updated statistics will include asterisks per rules set by the SBRC in 1969. “Baseball is so stat-related,” Mr. Wimbish, author of “Elston and Me: The Story of the First Black Yankee,” said. “That’s what makes baseball what it is — stats.”

The founder of MLBbro.com, Rob Parker, said the gesture by Major League Baseball shouldn’t be taken lightly. “To do something most people would push back on says a lot about Major League Baseball taking action more than just words,” Mr. Parker told the Sun. “To change the stats of major league baseball is ground-breaking. You don’t displace Ty Cobb as the all-time greatest batting average holder overnight and not be serious about your intent.”

MLB is scheduled to pay tribute to the legacy of the Negro Leagues on June 20 when the San Francisco Giants and St. Louis Cardinals play at Rickwood Field at Birmingham, Alabama, the former home of the Birmingham Black Barons.