NBA team front offices had four black presidents and CEOs this season -- more than all other U.S. major professional sports combined -- earning the league high marks for the second straight year in a diversity study released Wednesday.

The league has received top grades among men's leagues in all 12 previous studies from the University of Central Florida's Institute for Diversity and Ethics in Sport, and for the second straight year got an overall B+.

The president/CEOs were Terdema Ussery with the Dallas Mavericks, the Charlotte Bobcats' Ed Tapscott, Billy King with the Philadelphia 76ers and Steve Mills with the New York Knicks and WNBA's New York Liberty.