Basically, when Flacco was the mediocre quarterback who got hot in the playoffs and led his team to a championship, he was 27 years old and at his absolute peak.
Since then, he’s had one more good season (2014) and five sub-par seasons.
Lo and behold, after completing 67.6 percent of his passes in 2017, Keenum’s completion rate dropped to 62.3 with Denver. They were able to overcome the deficiency in 2015, thanks to a world-class, dominant defense.
But that's typically what happens when you finish first in the NFC.