That's going to be true throughout the Payton years if that's the observation you're resting on. (And generally true of this era of football.) I already pointed out that there were eleven games over the next two seasons where the Saints failed to score at least 21 points vs that happening twice in 2012. Considered as a measuring stick of performance to this specific point, that's not meaningless.
As it is, the 2012 defense was historically bad while the offense performed at a high level relative to the rest of the league that year, and consistent with the expected standard under Payton.