Complex sentence: Schalke's play fell off and the best they could manage in the new Oberliga West in 1947 was a sixth-place finish; within two years, they slipped to 12th place.
Split into simpler sentences: Schalke's play fell off and the best they could manage in the new Oberliga West in 1947 was a sixth-place finish. Within two years, they slipped to 12th place.