Welcome to the 2013 version of Insider's offseason staple series: Red Flags. This is the seventh of an eight-part examination in which Football Outsiders identifies the biggest remaining issue for every NFL team, division by division, after the NFL draft.
Here is the Outsiders' look at the NFC South:
Atlanta Falcons: Defensive end
The Falcons were a pretty good defense last season when they blitzed, but they couldn't get pressure on the quarterback with a standard four-man rush. When rushing five or more, the Falcons gave up 5.5 yards per play, making them one of the 10 best defenses in the NFL. When rushing exactly four, however, they gave up 7.4 yards per play. That was better than Kansas City (by about a quarter-inch per play -- seriously), but worse than every other team.
The Falcons addressed this by releasing John Abraham and signing Osi Umenyiora in free agency, but it's hard to call that an upgrade. Since missing all of 2008 with a knee injury, Umenyiora has 33.5 sacks. In the same four seasons, Abraham has 38.0 sacks, and he has had more sacks than Umenyiora in each of the past three years. Umenyiora is three years younger than Abraham, which is significant, but this still looks like a lateral move at best.