By John Turney
And here are the top defensive performances from 1973-77, the five seasons previous to the 1978 rule changes. It's pretty clear the dead ball era (great defensive era) was over.
Fewest Yards Allowed
Fewest Rushing Yards
Defensive Passer Rating
This was a big jump and the Steelers and their amazing 41.2 from 73-77 was something that just couldn't be duplicated with the new rules. The Steelers still did well, ranking fourth after being first in their previous five years.
Passing Yards Allowed
It's clear the passing numbers really jumped as did points, but the sacks and run stopping (fronts) didn't change much. The NFL, defensively, was becoming a coverage league rather than a front league and that trend has continued to this day.