PHOENIX -- A diversity report released Friday on Major League Baseball showed a modest increase in its overall diversity hiring practices, spurred by its improved gender diversity.

The Institute for Diversity and Ethics and Sport at Central Florida gave MLB an overall score of 80.7, which was a letter grade of B. That's up from a 79.5 in 2019. The grade for racial hiring dropped slightly from 89.4 to an 88.7 for a B-plus while gender hiring increased from 69.6 to 72.7 for a C.

Richard Lapchick, the institute's director and lead report author, called baseball's gender hiring improvement a "highlight" of this year's study. At the beginning of the 2020 season, there were 21 women who had on-field coaching or player development positions, which is up from seven in 2018.

"It wasn't that long ago that a thought about a woman on the field was not in anyone's consciousness," Lapchick said. "Having 21 women on the field is a dramatic jump. I think everyone saw that when the NBA started hiring and interviewing women there was a positive public reaction. MLB knew that would be good on the game."

The study said one of the sport's biggest diversity challenges was that the overwhelming portion of majority owners -- 39 of 40 -- were white. The one who is not is Arturo Morales of the Los Angeles Angels. He's the only Latino majority owner in American professional sports.

The final grades were calculated slightly differently this year. For the first time, the grade included hiring practices for team CEO/presidents and team vice presidents, which hurts MLB's final score. Lapchick said that would be the case for most every American sport.

"Baseball improved in a lot of areas," Lapchick said. "It's the leadership at the top that still needs to be addressed."

MLB received an A-plus grade for race in a few areas, including the MLB central office, players and coaches. The league also received an A-plus grade for diversity initiatives.

On 2020's opening day, 39.8% of the league's players were of color, down from 41% the past two years. Only 7.5% of opening day rosters consisted of Black players, the lowest percentage the study has recorded since it was started in 1991.

The Seattle Mariners had nine Black players on its roster, tops in the majors.

The diversity study is usually released on April 15 for baseball's Jackie Robinson Day, but baseball moved the celebration to Friday because of the coronavirus-disrupted schedule. MLB shifted Jackie Robinson Day to Friday, and the study was delayed until then.

The study says MLB's first-year player draft is providing signs that Black players might increase at the big-league level. Over the past nine seasons, more than 17% of first-round picks have been African Americans.

Six of MLB's 30 managers are Black or Latino, an increase from five a year ago. There are only four minority general managers.