The Chicago Bears have been historically a defensive team. A football team that has not found its stride with quarterback play. I wrote a piece on the history of the Chicago Bears here if you want to read more on how it has been.
Not all of those teams were lousy football teams. In the 1980s and early 1990s, the Chicago Bears used a combination of running the ball and defense to be successful. The same can be said for the 1950s to the 1960s. The NFL has changed a lot over the years and has evolved into a passing league.