Chicago stomped Seattle 37–6 on October 1, and on paper, it looks like the sequel should end in similar fashion. Football Outsiders’ Defense-adjusted Value Over Average ratings (DVOA) — which break down each play of the season and compare it to the NFL average based on situation and opponent — ranked Seattle 25th overall, while the Bears were fourth.

But the Bears haven’t been the fourth-best team in the NFL in recent weeks, or even a top 10 team. That vaunted Chicago defense declined in December, and everyone is waiting for quarterback Rex Grossman to self-destruct.

WHEN THE BEARS HAVE THE BALL Numbers can’t describe how badly Grossman is playing. He’s constantly flustered by pass pressure and misses open receivers all over the field. Grossman had reasonably good games against St. Louis and Tampa Bay late in the year, but that wasn’t Grossman fixing his problems; that was Grossman facing two very bad defenses.

On the surface, Seattle also seems like a bad defense that Grossman can handle, especially since they’ve been hit with a barrage of injuries in the secondary. There’s a small chance that starting cornerback Marcus Trufant will play; otherwise, with three of their top four cornerbacks injured, the Seahawks will start rookie Kelly Jennings and safety Jordan Babineaux. Nickel back Pete Hunter was working a desk job until two weeks ago.

But there’s an important difference between the Seahawks and those other teams: The Seahawks have a pass rush. It isn’t quite as strong as 2005, when the Seahawks led the league in sacks, but it’s plenty stronger than the Rams or Buccaneers. Last week, their front four put enough pressure on Dallas quarterback Tony Romo to allow the linebackers to give the weak defensive backs help in zone coverage. If the pass rush forces Grossman into mistakes, it won’t matter who the Seattle cornerbacks are.

While Grossman has faltered, the running game has improved. Over the first half of the season, veteran Thomas Jones averaged 3.8 yards per carry; in the second half, his average is 4.4 yards per carry. His backfield partner, Cedric Benson, gained 4.7 yards per carry over the last eight games and is finally fulfilling his promise as last year’s fourth overall pick.

But Grossman will have to throw the ball occasionally, and every time he drops back to pass, Chicago fans will hold their breath.

WHEN THE SEAHAWKS HAVE THE BALL Seattle fans blamed the Seahawks’ offensive woes on injuries to quarterback Matt Hasselbeck and running back Shaun Alexander. But Seattle’s offensive numbers haven’t changed at all since the two stars returned, and the Seahawks offense finished 27th in DVOA.

Chicago’s ferocious defense dominated Matt Hasselbeck when these teams first played, and defensive tackle Tommie Harris led the way. While he only had two official sacks, it seemed like Harris started every play by tossing a double team aside and ended every play sitting on top of Hasselbeck.

But Harris won’t be playing this week. He suffered a season-ending injury against Minnesota in Week 13 — and without Harris to provide pressure, the Chicago pass defense has faltered. The Bears allowed 4.6 net yards a pass with 21 interceptions in the first 12 games, but 6.0 net yards a pass with only three interceptions in the final four. Sacks per pass play have nearly dropped in half.

Chicago’s tendency toward zone coverage usually lets an opposing quarterback find his favorite target if he manages to stay upright, but it’s hard to tell who is Hasselbeck’s no. 1 target right now: early-season trade acquisition Deion Branch, last week’s top receiver Bobby Engram, or Darrell Jackson, who will return from a toe injury that cost him four games

So Hasselbeck will likely spread his passes around, to everyone except tight end Jerramy Stevens. He scored two touchdowns against Dallas, but Chicago has the best defense in the league against tight ends.

OUTLOOK Even with their recent defensive problems, Chicago is the heavy favorite in this game. Seattle’s offense has been subpar all year, and the secondary is put together with scotch tape. But what if Hasselbeck and Alexander can find their Super Bowl form of 2005? And what if Grossman has problems from the very first snap?

Head coach Lovie Smith insists that Grossman is not on a short leash, and under no circumstances will he pull Grossman for backup Brian Griese. But if Grossman throws an interception or two early on, can Smith possibly stick to that statement, knowing it might cost the Bears their best chance at a Super Bowl title in 20 years?