Season is over for Seahawks' Lofa Tatupu

RENTON — Seattle is the only team in the NFL to author two shutouts this season.

Those are also the Seahawks' only two victories. They're 0-4 when their opponent scores, and on Thursday, Seattle learned that its defense will lose one of its captains for the year as linebacker Lofa Tatupu underwent surgery to repair a torn pectoral muscle. He will be placed on injured reserve, likely replaced on the active roster by cornerback Marcus Trufant.

The temptation is to lump Tatupu's injury in with the rest of the maladies that have sent this Seahawks' season fishtailing into an early ditch for the second consecutive season. Quarterback Matt Hasselbeck has a couple cracked ribs, cornerstone tackle Walter Jones' story ended before it ever began and the Seahawks were an injury or two from checking under the I-90 interchange in their search for able-bodied blockers along the offensive line.

Except injuries don't explain the fluctuations in Seattle's defensive performance. At least not in the eyes of its coordinator.

"Offensively, there are some injuries that have taken place that maybe hurt their consistency," said Gus Bradley, Seattle's defensive coordinator. "I can't sit here and talk to you and say those same things."

Sure, Leroy Hill missed five games with a groin injury, Trufant has only been practicing for two weeks now, and Tatupu already missed one game, being replaced by David Hawthorne for the Week 3 game against Chicago.

"Heater jumped in and had 17 tackles against Chicago," Bradley said of Hawthorne's performance. "We were fine. We need to just continue to build on the positives that we're seeing."

And there are some positives. Seattle is No. 12 in the league in yards allowed and tied for seventh in scoring defense. The Seahawks defense has been like a coin this year. It has two sides.

"We're inconsistent," Bradley said.

The defensive performance can vary from week to week or even possession to possession. In their last game against Arizona, the Seahawks gave up an 80-yard, 11-minute drive to start the game and didn't force a punt until the Cardinals' fourth possession.

But look a little deeper. Four of Arizona's five scoring drives began on Seattle's half of the field, and the Cardinals gained only six first downs in the second half.

As head coach, Jim Mora hasn't spent much time addressing the defense as a unit. As coordinator, Bradley usually speaks to the defense, but the day after that game against the Cardinals, Mora made an exception.

"They do have some ability," Mora said. "They do believe in the system. So they're getting better. I told them that."

The defense must find a way to overcome the split-personality disorder that has plagued it so far this season.

"We shut out a team," Bradley said, "and all of a sudden we give up 27 points."

That was the Week 6 loss to Arizona.

"Or 25 points," Bradley continued.

That was the Week 3 loss to Chicago.

"Or whatever's the case," Bradley concluded.

That catch-all category certainly describes the 34-point clunker of a performance the defense rolled out in Indianapolis back in Week 4. The Seahawks allowed four touchdown drives of more than 75 yards in the Colts' blowout victory.

Sunday in Dallas, the Seahawks play a team that is No. 2 in the league in total yards. Cowboys receiver Miles Austin has more than 400 yards receiving in the past two games.

"We've got to come out fast and keep believing," Bradley said. "We know that sometimes they're going to score. Dallas, there's a good chance they could score on us. A good chance."

Responding to an opponent's points has posed a problem to Seattle so far this season.

Danny O'Neil: 206-464-2364 or doneil@seattletimes.com