Complex sentence: They tied for the Eastern Division regular season title with a 9--3 record by defeating the Cleveland Browns 13--10 on the last day of the regular season, and beat them again a week later in a one game playoff to determine the division winner.
Split into simpler sentences: They tied for the Eastern Division regular season title with a 9--3 record by defeating the Cleveland Browns 13--10 on the last day of the regular season. They beat the Browns again a week later in a one-game playoff to determine the division winner.