The first half of the 2006 season belonged to the Chicago Bears. The offense was powerful, the defense flawless. Even when the offense had an off night, as it did during a Monday night near upset by Arizona, the Bears could not be beat.

That Arizona game was not an off night, however; it was a preview of what was to come. As quarterback Rex Grossman went from inconsistent to just plain awful, the Chicago offense imploded. In December, even the defense began to lapse. The Bears won their first seven games by a combined score of 221–69. In their final nine games, they outscored opponents just 206–186, and last week they needed overtime to beat a subpar Seattle team that backed into the playoffs by virtue of playing in the NFL’s weakest division.

The season no longer belongs to the Chicago Bears. Instead, it now may belong to the New Orleans Saints. The Saints are trying to finish the greatest one-season turnaround in NFL history. They are not just a sentimental favorite; since midseason, they’ve clearly been the better team. Now they must brave the freezing temperatures of Soldier Field and attempt to write the next chapter in their amazing story.

WHEN THE SAINTS HAVE THE BALL Two injuries precipitated Chicago’s December decline on defense. The Bears had already lost strong safety Mike Brown at midseason, but his replacement, Todd Johnson, injured his ankle in Week 12. The following week, defensive tackle Tommie Harris tore a hamstring and was lost for the year.

Harris is a huge loss; Chicago’s cover-2 defensive scheme depends on the front four to generate pass pressure so that seven men can drop into zone coverage. The Bears allowed 4.6 net yards per pass with 21 interceptions in the first 12 games, but 6.0 net yards per pass with only three interceptions in the final four.

Johnson returned healthy against the Seahawks, and things did get better. The Bears allowed Matt Hasselbeck 5.0 net yards per pass, more in line with their earlyseason numbers. But Seattle wasn’t exactly one of the best offenses in the league this year. New Orleans is a different story.

Football Outsiders’ Defense-adjusted Value Over Average ratings (DVOA) — which breaks down each play of the season and compares it to the NFL average based on situation and opponent — rated the Saints as the best passing game in the NFC this season. Quarterback Drew Brees led the league with 4,418 passing yards, throwing 26 touchdowns with just 11 interceptions and 18 sacks.

Combine the Saints’ pass protection with the absence of Harris, and Brees should have plenty of time to find his favorite target downfield. Even when their defense was the best in the league, the Bears gave up an above-average DVOA to no. 1 receivers.

Although veteran Joe Horn may finally be returning from the groin injury that has kept him out for six weeks (he’s listed as questionable), that favorite target will probably be Marques Colston, the seventhround rookie from Hofstra who emerged as one of the league’s best possession receivers. Colston led the league with 29 conversions on third or fourth down, and Brees will find him for plenty of midrange gains between the safeties playing deep and the cornerbacks and linebackers playing short.

The Saints’ other receivers may not have as much success. Billy Miller led the Saints in receiving yardage against Philadelphia, but the Bears were the league’s best defense against tight ends. Speedy Devery Henderson won’t find it easy to get behind a secondary that gave up only 37 passes of 20 or more yards, the lowest total in the NFC.

The Bears are an above-average defense against the run as well, and when the pass defense declined, the run defense did not. Unlike last week, Deuce McAllister won’t have an easy time gaining yardage consistently. The Bears gave up some long runs once running backs reached the secondary, so there may be some Reggie Bush magic. But the Bears ranked third in defending passes to running backs, so that magic is more likely to come on a pitch or draw, not a swing pass.

WHEN THE BEARS HAVE THE BALL On the surface, Grossman’s numbers against Seattle last week look good: 21-for-38, 282 yards. But the raw yardage numbers hide his inability to move the chains on third down. He converted only three of 14 pass attempts on third down, with two sacks and two turnovers.

Grossman had a problem converting third downs throughout the second half of the year. He may have better luck than usual against the Saints, who were an average defense against the pass on first and second down, but ranked 25th in DVOA on third down.

But Grossman’s biggest weakness, making stupid mistakes under pressure, happens to correspond with the strength of the New Orleans defense: the pass rush, led by defensive ends Charles Grant and Will Smith. Based on sacks per pass attempt, the Saints get to the quarterback more often than the Bears do.

At least when Grossman forces a throw rather than taking a sack, a turnover is unlikely; the Saints had only 11 interceptions all year. (If they win, this will be the lowest total for a conference champion since the NFL went to a 16-game season.)

Just as the New Orleans defense’s biggest strength matches Grossman’s weakness, so too does its biggest weakness match Grossman’s strength: throwing deep, particularly to the speedy Bernard Berrian. Cornerback Mike McKenzie has played well, but the other Saints starter, Fred Thomas, has been consistently burned deep all season. Last week, Thomas gave up a 75-yard touchdown to Philadelphia’s Donte Stallworth. Every time the Saints let Berrian get behind Thomas without deep safety help, they are inviting the Bears to score seven points.

The Bears will run the ball plenty with veteran Thomas Jones and last year’s top pick, Cedric Benson, both to help Grossman and to keep Brees and the New Orleans offense off the field. The Bears run best up the middle, but against the Saints they should try to run behind left tackle John Tait. The Saints’ best linebacker, Scott Fujita, plays on the strong side (normally the right), so the Saints were weaker against runs to the offensive left.

As bad as the Saints were against the pass on third down, they were even worse against the run — but the issue there is third-and-long, not third-and-short. The Saints were the only team in the league to allow a first down on more than half of all runs on third/fourth down with four or more yards to go. But they were also one of only three teams in the league to stop a first down on more than half of all short-yardage situations (1–2 yards to go, including goal line).

The Saints defense is also at its best in the most important area on the field: the red zone. After all, it’s hard to burn the defensive backs deep when there’s less than 20 yards behind them.

SPECIAL TEAMS With rookie return man Devin Hester and kicker Robbie Gould leading the way, Chicago put up the second-highest special teams rating in the 10 years for which Football Outsiders has play-by-play breakdown. Hester set an NFL record with six return touchdowns, ranking second in punt return average and fifth in kickoff return average. Gould was excellent on both field goals and kickoffs.

The Saints have made a couple of moves to improve their otherwise average special teams. Forty-threeyear-old kicker John Carney is deadly accurate on field goals, but has no power; the Saints have been much better on kickoffs since adding a kickoff specialist, Billy Cundiff. They will also probably use Bush to return punts, and he’s more likely to make a game-changing play than the other Saints return man, Michael Lewis.

OUTLOOK The main question revolving around the Chicago Bears is no longer, “Which Rex Grossman will show up?” It is now ” Which Chicago defense will show up?” Even if Grossman is able to protect the ball against the unimposing Saints defense, the Bears can not win this game unless they can summon a top defensive performance to stop Brees, Colston, Bush, and McAllister.

The Saints have never gone to the Super Bowl. No dome team has ever won a conference championship game outdoors. No 3–13 team has ever made the Super Bowl the following season. The odds say that by Sunday night, none of these statements will still be true.

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