Mark Cuban, the billionaire owner of the Dallas Mavericks, has revoked credentials for two journalists who cover the NBA team, without giving so much as an explanation. The reporters are Tim MacMahon and Marc Stein of ESPN. “It’s between us and ESPN,” Cuban said, adding that they wouldn’t be allowed to cover the team’s games, but would still have access to the arena, the American Airlines Center. A spokesman for ESPN said the network is “committed to thoroughly covering the Mavs and the NBA.” The move is highly unusual, and it is rumored that Cuban was unhappy with ESPN for reducing its coverage of the Mavericks.