Complex sentence: In the 2015 season, they dropped to 10-6, lost the NFC West title to the Arizona Cardinals, and thus, enter the 2016 playoffs as the number 6 seed in the NFC.
Split into simpler sentences: In the 2015 season, they dropped to 10-6 and lost the NFC West title to the Arizona Cardinals. However, they entered the 2016 playoffs as the number 6 seed in the NFC.