When the Broncos went to the Super Bowl in 2013, Peyton Manning threw 55 touchdown passes and the team put up more points (606) than any team in NFL history. It was truly one of the most electric offenses the league has ever seen.
Though not quite as unstoppable the following year, the team still averaged 30.1 points per game in 2014. It has been a steady decline since, with a small sign of improvement this past season.
Manning began to physically decline in 2015 and though the Broncos won the Super Bowl thanks for a great defense, the team dropped down to an average of 21.