Complex sentence: Increasingly erratic and brutal as he struggles to keep order, Rick steps down as the group's leader, replaced by a committee run by him, Hershel, Tyreese, and the group's oldest and wisest member Dale.
Split into simpler sentences: Increasingly erratic and brutal as he struggles to keep order, Rick steps down as the group's leader. He is replaced by a committee run by him, Hershel, Tyreese, and the group's oldest and wisest member Dale.