By now, most NFL teams know if they’ll be playing in January or not. But some teams are still on the bubble, where every game is a must-win.

CHICAGO (9-3) AT PITTSBURGH (7-5) (Sunday, 1 p.m.)

On the surface, Chicago and Pittsburgh are similar teams, but they could not be going in more divergent directions. The Bears have won eight straight games and hold the inside track on a first-round bye in the NFC. The Steelers have lost three straight and, after falling to Cincinnati last week, basically must win out just to have a chance at an AFC wild-card spot.

Chicago quarterback Kyle Orton is in the same position now that Pittsburgh’s Ben Roethlisberger was last year, leading a team built around defense and a running game to a succession of wins. But the comparison should end there, because while Roethlisberger complemented last year’s Pittsburgh running game with precision passing, Orton has been one of the worst quarterbacks in recent memory.

Last season, Roethlisberger completed 66% of his passes, averaging 8.9 yards per attempt. Orton completes just 53% of his passes, averaging 5.1 yards per attempt. Orton also has 13 interceptions and 11 fumbles against nine touchdown passes.

Chicago’s offense isn’t entirely abhorrent. Thomas Jones has been surprisingly productive as the starting running back, and Muhsin Muhammad is still a talented wide receiver. But those strengths play right into the teeth of the Pittsburgh defense. The Steelers allow just 3.4 yards per carry, the lowest in the NFL. And according to Football Outsiders’ Defense-adjusted Value Over Average system (DVOA) – which breaks down each play of the season and compares it to the NFL average based on situation and opponent – Pittsburgh’s pass defense ranks third in the league against no. 1 receivers, even though it is just average against second and third wideouts.

Because Chicago is so good on defense and so bad on offense, their recent run of glory has not featured many convincing victories. Although their eight game win streak began with a 28-3 trampling of Minnesota, the Bears have won the other seven games by an average of just 6 points. Five of the wins came over teams that are 4-8 or worse.

The good news for the Bears is that Pittsburgh resembles Chicago’s most impressive victim this season: the Carolina Panthers. Pittsburgh’s offense, like Carolina’s, is predicated on a strong running game which hasn’t been so strong this season. After a fast start, Willie Parker has dropped to just 3.7 yards per carry in his last four games, while Jerome Bettis is averaging less than three yards per run.

Like Carolina, Pittsburgh’s passing game depends heavily on a single receiver who can beat one-on-one coverage (Hines Ward) but rare sees such coverage because the team’s other receivers have been subpar.

And with the running game unable to match its performance from last season, Roethlisberger has developed a nasty habit of forcing passes into coverage and throwing costly interceptions, much like Carolina quarterback Jake Delhomme.

Add to this the disarray on the Steelers’ offensive line, particularly injured left tackle Marvel Smith being replaced by rookie Trai Essex, and the best offensive strategy for Pittsburgh might be simply to avoid offense, get into a field position battle with Chicago, and wait for a mistake either by Orton or punt returner Bobby Wade, who has twice as many fumbles as any other returner in the NFL.

KANSAS CITY (8-4) AT DALLAS (7-5) (Sunday, 4:15 p.m.)

The precarious playoff position of these two teams is just one reason why this game provides an interesting matchup. In an odd twist, DVOA ranks Kansas City sixth in offense and 14th in defense, and Dallas the exact opposite, 14th in offense and sixth in defense. Each team has had half a strong defense in 2005: Kansas City can stop the run, while Dallas fares much better against the pass.

But for the second straight week, the Cowboys will be facing a team whose preferences in the passing game match their weaknesses. Like the Giants, the Chiefs depend heavily on a star tight end (Tony Gonzalez) and a single wide receiver (Eddie Kennison), with other wideouts relegated to minor roles. According to DVOA, Dallas leads the NFL in preventing success on passes to no. 2 receivers but is 20th against no. 1 receivers and 23rd against tight ends.

Dallas must also deal with running back Larry Johnson, who is averaging 5 yards per carry. The Cowboys’ run defense has been just average during the season, and has particular problems in short-yardage downs, stopping just one of 13 runs on third- or fourth-and-1.

The Cowboys expected a similar breakout year from Julius Jones, but he was derailed by injuries for much of the year. Jones and his backup, rookie Marion Barber, are combining for just 3.6 yards per carry. Last year’s Kansas City defense couldn’t stop a crawling toddler from amassing 150 yards on the ground, but an improved front seven has turned that around. This year’s Chiefs allow just 3.7 yards per carry, so long as the ball carrier is not wearing a Denver Broncos uniform.

Of course, why try to run on the Chiefs if you can pass on them? The Chiefs play an aggressive style of defense, trusting their cornerbacks to play man-to-man. This leads to a lot of long pass plays – the Chiefs give up 12.2 yards per reception, the third-highest average in the league. Their blitzing linebackers leave the middle of the field open, which presents Dallas with a dilemma. The Chiefs rank 29th in defending tight ends, and Dallas’s Jason Witten is one of the league’s best. But Drew Bledsoe only succeeds when he has time to throw, so the Cowboys want to leave extra blockers to pick up the pass rush. Expect a lot of the two-tight end set with Witten as a receiver and Dan Campbell staying in to block.

The x-factor in this matchup is home field advantage. Contrary to conventional wisdom, Kansas City hasn’t been much better at home than on the road. But for the Cowboys, the difference has been remarkable. At home, they’ve gained 5.0 yards per play and allowed 4.7. On the road, they’ve gained 4.7 yards per play allowed 5.0.

Mr. Schatz is the editor in chief of FootballOutsiders.com.