RENTON, Wash. — First, it was his back. Then, Matt Hasselbeck’s knee, followed by blows to the head. Now, it’s the one thing he and the Seahawks have relied upon for most of this decade: his passing.

Yes, Hasselbeck has had better years. He can’t even take comfort by dreaming of Hawaii, where he went to play in the Pro Bowl for the third time last February.

“Not going to be doing that this year,” the NFL’s lowest-rated passer said.

The Seahawks are 2-9 entering their Thanksgiving game at Dallas. It’s their worst start since 1992.

They’ve had injuries on the offensive line. They’ve had seven injuries at wide receiver.

Hasselbeck is throwing to one receiver, Koren Robinson, who was on his couch in Raleigh, N.C., when the season began. His other top target, Deion Branch, is nine months removed from reconstructive knee surgery. Bobby Engram, Hasselbeck’s usual go-to player on third downs and crucial plays, is getting most of the attention from opposing defenses who have no one else to worry about with the league’s 31st-ranked passing offense.

Despite the lack of a consistent running game and a suspect offensive line in 2007, Hasselbeck carried Seattle to its fourth consecutive NFC West title and set most of the team’s passing records for a single season.

Coach Mike Holmgren had said “I guarantee you” this lost season would flip once Hasselbeck and, to a lesser extent, Branch returned. The 33-year-old Hasselbeck missed five games with a bulging disk in his back that caused nerve problems and weakened his hyperextended right knee.

Yet Hasselbeck has doomed the Seahawks’ last two chances for season-reviving upsets, against Arizona two weeks ago and last weekend against Washington, with late interceptions.

Holmgren said Tuesday for the first time that Hasselbeck essentially played with a concussion and was affected by it after a hit to the head in the first half against the Cardinals.

“Yeah, I didn’t know it,” the coach said, though he was asked about a possible concussion the day after that loss that gave the Cardinals a big lead in the race for the division title on Nov. 16. “I asked him something before I sent him out there and he responded.

“You get dinged ... and you can kind of answer stuff and kind of fake people out a little bit. But yeah, he wasn’t really (with it).”

Asked about whether he had a concussion, Hasselbeck said: “How would I know? I don’t remember.”

But even when clear-headed this season, Hasselbeck hasn’t had it. He was the lowest-rated passer in the NFC through four games before his injuries.

“I think I would like to see the same thing (as his 2007) it’s a little unrealistic,” Holmgren said. “He’s played a couple games now. And so he’s working with some new combinations. To expect that — and I’ll be honest with you, I kind of hoped — but it’s not happening. Not right now.”

During those seasons with five consecutive playoff appearances, including Seattle’s only Super Bowl at the end of the 2005 season, Holmgren said how Hasselbeck had mastered his thoughts to make risky, sometimes unwise decisions with the ball.

Hasselbeck said he finally had gained an unspoken understanding with what Holmgren expected him to do in any situation — and was finally doing it.

Forced passes into coverage became prudent audibles to runs or safe dump-off passes that maintained possession.

Now, in his two games back from a nerve and back issues for which doctors initially told him he should miss the rest of the season to rest, Hasselbeck is forcing throws into coverage again.

The career 60 percent passer has reached that mark in just one game this season. He has yet to throw for more than 190 yards in a start. He has nine interceptions and five touchdowns in six games.

He is four years into a six-year, $47 million contract with $16 million in guarantees. His cap number is scheduled to be about $9.5 million in 2009, and the Seahawks may seek to re-negotiate his base salaries of more than $5 million for each of the final two years of his deal.

Holmgren was asked whether this season Hasselbeck has had warrants him reassuring his quarterback, before the coach leaves Seattle and takes a sabbatical from football in 2009.

“No. Matt Hasselbeck is a fine quarterback,” Holmgren said. “Just think about all the nice things you wrote about him last year. He has been hurt. He has battled like crazy to come back and play. I mean, that’s a big deal.

“Matt’s a very confident young man and he’s worked very hard to get into the position he’s in right now. He doesn’t really need any affirming from me anymore.”

Hasselbeck also calls 2008 an aberration.

“Definitely,” he said. “There are reasons why things are going the way they are.

“We are going to start over with a clean slate (in 2009).”