The Seattle Seahawks invested their first round draft choice on Bruce Irvin, a defensive end from West Virginia. Many in the national media saw this pick as a major reach, largely because Irvin is seen as a specialist and not as an every down player. His specialty is sacking the quarterback, and Pete Carroll and John Schneider saw him as the best sack specialist in this year's draft.
How important were sacks to the Seahawks defense last year? Here are some numbers to think about: In Seattle's seven wins they recorded 21 sacks, or three sacks per game on average. In their nine losses they mustered up only 12 sacks or 1.33 per game, though four of those sacks game in a game they lost against the Cleveland Browns, where the defense played great and only gave up six points. In the remaining eight losses they only had eight sacks.
The Seahawks had 33 sacks on the season. Twice they recorded two sacks on the same offensive possession, meaning their opponents had 31 possessions in which the Seahawks recorded at least one sack. Of these 31 possessions, the Seahawk's opponents only scored on five occasions, - two touchdowns and three field goals. Seahawks opponents were only able to score points 16% of the time when they were sacked by the Seahawks. They scored 23 points on those 31 possessions. That means on possessions where the Seahawks recorded a sack, teams averaged .74 points. Opponents scored 257 offensive points against the Seahawks on 158 additional possessions that did not include a sack for an average of 1.63 points per possession.* You can see how important sacks are for limiting scoring.
Of the 31 possessions in which Seahawk's opponents were sacked, 13 ended in punts, three ended in interceptions, three ended in lost fumbles, two ended with a turnover on downs, one ended the half, four ended in missed long field goals and five, as already mentioned, ended in a score - two TD and three FG. All three of these made field goals were quite long, however, and the lost field position from sacks certainly contributed to the four missed field goals.
There are, of course, some caveats to consider when looking at the above numbers. The major one being that teams are more likely to play aggressively when they are losing games, creating more passing situations and thus more opportunities for sacks. So it could be argued that winning creates sacks as much as sacks create winning. However it still remains abundantly clear that getting sacks limits opponent scoring and can contribute to offensive scoring through better field position.
Given these numbers, you can see why pass rush specialists are valued so highly in the NFL and why the Seahawks felt comfortable selecting Bruce Irvin as the 15th overall selection. It remains to be seen if it was a good pick or not, but if he can deliver sacks, he will have definitely been worth the selection.
*Special thanks to Football Outsiders for compiling stats on all possessions.