Complex sentence: Boles was still in that position when the 1996 season began, when, on July 7, Marlins manager Rene Lachemann was fired, and Boles was named interim manager.
Split into simpler sentences: Boles was still in that position when the 1996 season began. But, on July 7, Marlins manager Rene Lachemann was fired, and Boles was named interim manager.