In the history of the National Football League, there have been few halftime scores as shocking as the 20–0 lead Arizona held on unbeaten Chicago two nights ago. And in the history of the National Football League, there have been few collapses as shocking as the one Arizona had in the fourth quarter, losing 24–23 to a Bears team that scored no offensive touchdowns and turned the ball over six times.

Fans can continue to relive this wild game on sports radio and the Internet all week, but the teams involved need to resist that urge and look forward. A miracle win makes Chicago seem like a team of destiny, but they won’t make it to the Super Bowl without fixing the problems that made the big comeback necessary.

Chicago outscored its opponents by 120 points in the first five games and looked like one of the top teams in every phase of the game: offense, defense, and special teams. It turns out this is twothirds correct, but Chicago’s offense imploded, and the main culprits were quarterback Rex Grossman, left tackle John Tait, and right tackle Fred Miller.

Chicago’s veteran line was probably the only part of the offense that was actually well regarded going into this season, but the Cardinals pushed them around all night.Arizona shut down the Chicago running game, and when the Bears dropped back to pass, defensive ends Chike Okeafor and Bertrand Berry continually tossed Tait and Miller aside with no effort and went straight after Grossman.

There was already evidence that defensive pressure on Grossman would result in big mistakes. It came during Chicago’s one close game before this one, a 19–16 win at Minnesota. Like the Cardinals, the Vikings pressured Grossman on nearly every pass. They only sacked him once, but that’s because as soon as Grossman saw a pass rush he would backpedal 11 or 12 steps and uncontrollably heave the ball into the air. Two of these balls came down in the hands of Vikings defenders, and one was run straight into the end zone.

On Monday, Grossman melted down again, but surprisingly, he did it in a different fashion.This time, he stayed in the pocket rather than moving backward, and on most of his passes he set his feet and saw his receiver all the way.The problem was that he didn’t see all the red uniforms around his receiver. Over and over, Grossman threw into coverage, to receivers who weren’t even close to being open. He also telegraphed his throws with his eyes and body language, making it easy for defenders to get a jump on them. On one interception, he threw the ball directly to linebacker Gerald Hayes. Somehow, Grossman didn’t see Hayes standing right in front of him, halfway between Grossman and receiver Bernard Berrian (who, by the way, had cornerback Eric Green right on top of him).

Grossman is frequently compared to veteran Green Bay quarterback Brett Favre because of his “gunslinger mentality,”but that mentality can be a negative. Grossman needs to learn to throw the ball away instead of constantly trying to make passes that just aren’t there.

The Bears also need to do a better job of protecting him, and this is where it gets tricky. Early in the season, opponents would bring their safeties up to stop the Chicago running game, and the Bears would take advantage by passing to tight end Desmond Clark running through open space vacated by the safety. Again in this week’s game, Clark was the leading receiver with four catches for 61 yards. But if they want to keep Grossman protected against a team with a strong pass rush, the Bears will have to leave the tight end as an extra blocker, and remove that weapon from their downfield arsenal.

Chicago’s defense dominated the fourth quarter, so it’s easy to come away with the impression that the problems are all on offense.But that’s not the case. The Bears play the “Tampa 2” style defense popularized by Tony Dungy when he was still with the Buccaneers. Their defensive backs and linebackers predominantly play zone coverage, not manon-man, and a smart quarterback can easily find the holes between defenders. Matt Leinart may be a rookie, but he’s a smart quarterback, and on nearly every pass he would find somebody open.The receiver would catch the pass with three defenders frantically running up behind him, trying to get to the hole in the zone in time to stop the first down. Arizona lost in large part because they stopped throwing the ball, and instead ran Edgerrin James into a wall of Chicago defenders over and over for no gain.

The offensive strategy against the Bears seems pretty clear now: Keep in multiple tight ends and/or running backs for maximum protection against the Chicago pass rush, and send the rest of your guys out to go find the holes in the zone. Leinart was also running a lot of quick drops, play-action rollouts, and plays from the shotgun formation. Those plays are designed to compensate for Arizona’s terrible offensive line, but they would work equally well for any team, simply to try to compensate for a Chicago pass rush where the best players — tackle Tommie Harris and linebacker Brian Urlacher — come up the middle. The Bears need to be willing to deviate from their zone coverage when a quarterback is taking advantage, and they need to work on some zone blitzes that drop those central pass rushers into coverage to confuse the quarterback.

Some sportswriters have suggested that an undefeated season is a bad thing. Better that your team’s holes be exposed while you can still fix them, instead of your team entering the playoffs with a false sense of invincibility only to find your holes exposed in a postseason loss. Chicago now knows what it needs to work on if it wants to turn Super Bowl hype into reality, and the good news for the Bears is that they didn’t even need to put a loss on their record to do it.

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