Complex sentence: In 1991, the upper deck seats were replaced by aluminum bleachers, which reduced its capacity to 44,008, and the artificial turf was replaced by natural grass at the request of the new coaching staff.
Split into simpler sentences: In 1991, the upper deck seats were replaced by aluminum bleachers which reduced its capacity to 44,008. The artificial turf was also replaced by natural grass at the request of the new coaching staff.