Complex sentence: The bottom two place finishing teams each year in the A1 division standings are relegated to the A2 Ethniki due to poor performance, while the top 2 teams each year from the A2 division are promoted to the A1 Ethniki due to good performance.
Split into simpler sentences: The bottom two place finishing teams each year in the A1 division standings are relegated to the A2 division, due to poor performance. While conversely, the top two teams each year from the A2 division are promoted to the A1 division, due to good performance.