CINCINNATI -- Reds general manager Dan O'Brien was fired Monday by new owner Bob Castellini, his first major change since he took control of the team. O'Brien was entering his third season as general manager and had a year to go on his contract. The Reds have had five consecutive losing seasons, their longest such streak in 50 years. Major-league owners approved the Reds' sale to Castellini last Thursday. In a news conference a day later, he indicated he was impatient with losing and was planning to make changes as he learned more about how the team operates.