There are several categories to rank an all-time great defense; points allowed, yards allowed, sacks, turnovers, DVOA, just to name a few, but a recent string of Tweets from Football Perspective (@fbgchase) has a new one I found interesting.
They took the ratio of touchdowns allowed, to punts forced plus turnovers gained and several Chicago Bears’ defenses landed on the list. In their all-time list, the Bears ended up 6th, 20th, and 26th, but in the post 1978 list, Chicago’s defenses were 1st, 7th, 9th, 15th, 34th, 41st, and 49th.