Complex sentence: This season is second time the show has a drastic change in the main cast with Noah Wyle's departure from the show Goran Visnjic's character Luka Kovač became the show's central character.
Split into simpler sentences: This season is the second time the show had a drastic change in the main cast. With Noah Wyle's departure from the show, Goran Visnjic's character Luka Kovač became the show's central character.