This fanpost isn't meant to be some statistical breakdown with the help of something on Football Outsiders. It's just a random drive-by observation before I hop back out and work on Enemy Reaction.
The incredibly cheesy title for the 2012 Seahawks Yearbook was "Learning to Finish", which is a very clear reference to their multiple late game collapses, primarily caused by the defense. On opening day, the defense was bossed by Kevin Kolb (coming in for the injured John Skelton) and let a 16-13 lead slip to a 20-16 deficit. After 27 attempts from the 5 yard line, the offense couldn't salvage a victory. In week 8, the Seahawks had a 24-21 edge on the Lions, only to completely fall apart and allow a late touchdown to Titus Young for a 28-24 loss. Against the Dolphins, Ryan Tannehill carved up Marcus Trufant en route to breaking a 21-21 tie and winning 24-21 at the gun. The defense nearly coughed up a 17-14 lead with 25 seconds left against the Bears, but luckily Russell Wilson saved the day in overtime. After several comfortable wins, the Seahawks had a 28-27 lead vs. Atlanta after being down 27-7, but ... you know the rest.
That is not to take away their stuffing of Green Bay or holding the mighty Patriots to 6 points in the 2nd half, but it was an undeniable problem. The defense was capable of fantastic play, but in the final minutes of a close game, they just kept giving up the losing points to the point where it fittingly cost them a berth in the NFC Championship Game.
So far the Seahawks have played 2 close games - vs. Carolina and vs. Houston.
Carolina
-- After the Seahawks took a 12-7 lead against Carolina, the Panthers (aided by two 15 yard penalties) were inside Seattle territory and ready to recapture the advantage. DeAngelo Williams saw daylight, broke inside the 10, and was brought down at about the 9 or 8 yard line ... without the football. The Panthers never saw the ball again.
Houston
-- Seattle miraculously rallied from 20-3 down to tie things up at 20-20. The Texans immediately marched to the Seattle 43, where the drive stalled and the game went to overtime. Houston's 1st possession ended at its own 40 before a punt. Their next (and last possession) went as far as the Houston 49 before Schaub went into fetal position and effectively killed off any chance at a field goal. The Seahawks won the game.
It's 4 games in, and in 2 games the Dan Quinn defense has definitely "finished" teams. As of yesterday, the Seahawks opponents are just 18 of 54 on 3rd down conversions, which stands as the best efficiency under Pete Carroll. These two improvements have been a huge reason for Seattle's 4-0 start, with 2 of them coming on the road against good teams -- Carolina is a good team with an extremely awful head coach.
Despite having the #1 scoring defense last year and not allowing any opponent to score more than 2 touchdowns at home, there was quite obviously room for improvement for this group. After 4 games, I'd say there's improvement across the board. The secondary has yet to allow a touchdown, as all 3 TD passes given up were on linebackers, they're now managing a pass rush on the road, and they've twice denied the opposition a winning score in the final minutes/overtime.
And guess what? This is the hard part of the schedule, where the road games are all clustered up. Have you seen the home games? The QBs include Ryan Fitzpatrick (Titans), Christian Ponder/Matt Cassel (Vikings), Mike Glennon (Bucs), Drew Brees (Saints), Carson Palmer (Cardinals), and Sam Bradford (Rams).
There's no denying how special this team is. And there's still some missing pieces (Irvin and Harvin) waiting to return.