Balls, an ambitious mashup of docudrama and satiric commentary, takes the Sept. 20, 1973, exhibition match between Wimbledon champs Billie Jean King and Bobby Riggs as a starting point for assessing social upheavals of the past 45 years. When Riggs challenged King to the match eventually dubbed the “battle of the sexes,” she was 29 years old. Riggs had won at Wimbledon four years before she was born. They squared off in front of more than 30,000 spectators in Houston’s Astrodome as millions more watched on television. Riggs lost in straight sets, 6-4, 6-3, 6-3, and King walked away with the “winner take all” purse.