BH90210 is part of Fox's experiment with shorter runs for shows

Variety

The nine-episode Beverly Hills, 90210 revival and the nine-episode What Just Happened??! With Fred Savage are part of the new Fox's mission to try shorter-run series. “You will see a variety of order patterns in comedy and drama,” says Fox Entertainment president Michael Thorn. “It’s a 52-week business, and we are really looking at our schedule and looking for ways to be more opportunistic about the way we launch shows.”