Complex sentence: He only spent one season with the Asturias side, and Oviedo finished the season penultimate, being relegated to division three, then demoted one stage further because of financial ireegularities.
Split into simpler sentences: He only spent one season with the Asturias side, and Oviedo finished the season penultimate, being relegated to the third division. They were then demoted one stage further because of financial ireegularities.