Detroit Lions' defensive weakness

Ndamukong Suh draws eyes to the Lions' D, but there's a glaring hole behind him. AP Photo/Carlos Osorio

The Detroit Lions suffered their first defeat of the season on Sunday -- a 25-19 loss to the San Francisco 49ers -- in large part because they gave up a series of big runs. While the vaunted Detroit defensive line is every bit as good as you've heard, it remains vulnerable to big plays on the ground.

That vulnerability, combined with an unreliable offense, largely explains why the Lions are still a long shot to finish ahead of the Green Bay Packers in the NFC North.

This season, the Lions are surrendering 5.2 yards per carry, the second-highest figure in the league behind the Chicago Bears. However, they look much better when viewed through the prism of Football Outsiders' advanced metrics.