Seahawks defense on a downturn

Defense was Seattle’s signature for the first six games of the season, the crutch the Seahawks leaned upon while the offense ground its gears.

But the defense was Seattle’s undoing Sunday — whether it was Chris Ivory leaving footprints as he ran over the Seahawks in the first quarter, or Drew Brees making like a marksman and putting the ball where he wanted, when he wanted.

It all added up 494 yards of total offense for New Orleans, and nothing showed its prowess more than its performance on third down, when the Saints converted 11 of 15 opportunities. Three of those plays were third-and-10 or longer.

“When we don’t play well on third down, we have trouble,” Seahawks coach Pete Carroll said. “That was what happened.”

Just as Seattle’s offense has begun to move the ball effectively, it appears its defense is slipping. Sunday was the third time in the past four games that Seattle has allowed more than 475 yards.

So what happened in New Orleans? Well, Brees happened, but there was a more fundamental problem, too.

“It was a lot of missed tackles,” linebacker Aaron Curry said. “We missed a lot of tackles that were turned into big plays. … Big plays always result of missed tackles.”

That’s true. Ivory spent a good chunk of the first quarter treating Seattle’s defenders like speed bumps, something to be rolled over.

But tackling doesn’t explain the passing yardage the Seahawks once again hemorrhaged, as for the third time in four weeks an opposing quarterback had a triple-digit passer rating against them.

Seattle’s defense also has suffered injuries. On Sunday, cornerback Marcus Trufant left the game with a concussion suffered in the first quarter, and was replaced by rookie Walter Thurmond.

The Seahawks were already missing two starters — defensive end Red Bryant was lost for the year with a knee injury, and defensive tackle Colin Cole is out because of an ankle injury. Both Bryant and Cole were injured against Oakland, the game that marked the start of the defense’s downturn. That can’t be a coincidence, can it? But Carroll wasn’t going to pin what happened Sunday to who wasn’t out there.

“What that has to do with injuries, I’m not going that way,” he said. “We just keep battling. We got to figure it out. There’s no question we miss Red. Red was a big factor for us, and we’ve been ringing that bell since we’ve been together, but other than that, we’re OK. We kind of keep fighting and scratching and clawing to get to ’em.”

This is the same defense, after all, that kept the team afloat early on. But this week that defense gave up too many touchdowns for Seattle to have much of a chance of winning this shootout.