The Detroit Pistons have agreed to a four-year contract with coach J.B. Bickerstaff with a team option for a fifth season, according to a person familiar with the situation. The person spoke to The Associated Press on condition of anonymity Sunday because the agreement had not been announced. The Cleveland Cavaliers fired Bickerstaff in May after they lost to Boston in the Eastern Conference semifinals despite them winning 99 games over two years. The Pistons fired coach Monty Williams one season into a six-year, $78.5 million contract after they had the NBA’s worst record for a second straight year.