Getty Images

Not since 1980 has an NFL team made it through a 16-game season while allowing less than 150 passing yards a game. This year, two defenses are on pace to do it.

Through Week Seven, the 49ers’ defense is allowing 133.5 passing yards per game and the Patriots’ defense is allowing 148.4 passing yards per game. That puts the 49ers on pace to allow 2,136 passing yards this season, and the Patriots on pace to allow 2,374 yards this season.

How rare is that? A pace of 150 yards a game would equal 2,400 yards in 16 games. In a 16-game season, no defense has allowed fewer than 2,400 passing yards since 1980. That year, Washington allowed an NFL-best 2,171 passing yards.

Whether the 49ers and Patriots can continue at this pace remains to be seen. It won’t be easy, as both teams face a better schedule of opposing quarterbacks over the next several weeks than they have so far this season. But that they’ve made it this far into the season holding opposing offenses to numbers that look like they’re out of the 1970s is remarkable.