The Baltimore Ravens have made the playoffs one time in the last four seasons. The Ravens had a grueling 5-11 season in 2015. The Ravens record since winning Super Bowl XLVII is 31-33. Baltimore went 10-6 in 2014 and beat the Pittsburgh Steelers in the first round of the playoffs. Other than that, the Ravens have been overall mediocre since climbing the NFL mountain top.
If the Ravens had fired John Harbaugh after their 8-8 2016 campaign it would have come as a surprise. That being said, coaches have been fired for a lot less in the NFL.