The Baltimore Ravens entered the NFL in 1996 and, like other expansion teams, it took them a few years to get off and running. It says a lot about how the Ravens are run that the worst year in their entire franchise history is the very first year they were in operations.
During that 1996 season, the Ravens went 4-12 and they've never had a record that's matched that ever since. That's pretty darn impressive. While the Ravens have had a five-win season, that four-win season in their inaugural 1996 campaign is still the fewest number of wins in a single season.