Great defenses? Not on third-and-long

NFL defense aspires to force opponents into third-and-long.

Good ones should feast on opposing offenses in these favorable situations.

NFC West defenses, though strong overall, have suffered from some puzzling third-and-long breakdowns. I'm not here to judge. It's tough to know for certain why defenses sometimes struggle to finish. Nickel corners could be to blame. Coordinators might need to adjust their strategies (in this case, sending five or more pass-rushers doesn't seem to make a huge difference). Sometimes, the opponents deserve credit.

The chart, from ESPN Stats & Information, ranks NFL teams by worst Total QBR allowed on third-and-8 or longer. I’ve included NFL passer rating figures as well (the Rams are excused from this discussion as they've fared better in these situations).

The San Francisco 49ers gave up a 50-yard gain to the Detroit Lions on a third-and-17 in Week 2, a play coach Jim Harbaugh called perhaps the team's worst defensive play during his tenure with the team. Minnesota's Christian Ponder completed a 14-yard pass against the 49ers on a third-and-10. Even Mark Sanchez, wholly ineffective for the New York Jets in Week 4, managed a 22-yard pass to Chaz Schilens against the 49ers' defense on a third-and-15 early in the game.

The Arizona Cardinals allowed a 51-yard touchdown pass Thursday night on a third-and-11 play against the St. Louis Rams. A week earlier, the Seattle Seahawks could not stop the Rams from gaining 26 yards on third-and-13. The Rams also gained 15 and 19 yards on third-and-10s, and 14 yards on third-and-13.

This is a trend to follow as the season progresses.

2012 Worst Pass Defenses: Third-and-8 or Longer