It's called a confidence interval in statistics and a safety calculation in engineering. In professional football it's a less formal computation of the number of stupid mistakes you can make while still managing to win a game. Welcome to the fascinating reckoning known as margin of error.
A quarter of the NFL has opened the season with a 2-0 record, including the Bears, the only team to do it with two home games. The eight road victories for unbeaten teams have featured only one victory for a team losing the turnover battle — the Patriots beating the Bills despite a minus-1 turnover ratio.
That's a polite way of reminding the Bears they must clean up some things to continue their perfect season in Pittsburgh on Sunday night, even if the proud Steelers clearly are struggling at 0-2. Two weeks into the season, only two teams — the aforementioned Patriots and the Chargers — have pulled off road victories with negative turnover ratio. It's a simple fact of NFL life that you can't make mistakes and win on the road.
The Bears had four turnovers against the Vikings, gave up a defensive touchdown and a kickoff return and still managed to drive down the field for a victory in the waning seconds. That's a recipe for disaster on the road, where the crowd, and often the officials, can be hostile.
While not exactly the Blanche DuBois of the NFL, the Bears have relied on the kindness of strangers in their two opening victories. First came the Bengals, who burned timeouts and made stupid, undisciplined penalties that led to a field goal before halftime and a first down at the end of the game.
The Vikings weren't quite that bad, but they nonetheless bungled badly when it mattered most as well. They were caught in the wrong coverage twice on the decisive drive, including a play of outright confusion during which no one knew where to line up on the winning touchdown when they could have called timeout.
Quarterback Jay Cutler, who led an impressive comeback from an 11-point deficit in the opener, was equally impressive in Week 2 except for three bad plays — two interceptions and a fumble that was returned for a touchdown. Cutler is growing comfortable and confident in coach Marc Trestman's version of the West Coast offense. The Bears are protecting him well and holding the reins tight on his gambler's instincts while encouraging him to spread the ball beyond the solace of Brandon Marshall.
"Marc Trestman has put $70 million to $80 million right in his pocket because he has cleaned him up,'' CBS analyst Phil Simms said.
Cutler, of course, will be out of contract at year's end, and Simms' figures might be low.
The last two times the Bears opened 2-0, they wound up in the NFC championship game, with one trip to the Super Bowl. It's far too early to predict another such run, but the good news is they have shown an ability to overcome mistakes.
Where once the Bears were incapable of overcoming any errors and a punt might have been considered a positive play, now the offense is expected to produce. Where once the franchise relied on defense and special teams to win and the offense was only required not to screw up, now there is shared responsibility.
The Trestman era marks an end to the three-downs-and-a-cloud-of-punts offense that staggered the team for years. Through two weeks, the Bears rank 14th in the NFL on offense, averaging 367 yards per game. They are tied with the Lions at No. 6 in scoring with 55 points. It might not sound like much now, but the only time since 2000 the Bears have been in the top half of the league on offense, they wound up in the Super Bowl.
There are plenty of reasons for concern. Whenever Peanut Tillman limps or Julius Peppers disappears, the organization holds its collective breath. Tillman isn't the best cornerback in the NFL, but he's the best system fit in the league. And he's an essential playmaker at a position where the Bears are dangerously thin. One longtime NFL scout said Tuesday that the Bears are very thin at cornerback and predicted teams would start to go after Isaiah Frey at nickel back.
That will happen especially if the Bears don't improve their pass rush. It goes back to the definition of margin of error in engineering: the strength of the material minus the anticipated stress. The Bears only will be as good as their front-line talent can carry them, and those guys must be healthy to play well.
The Steelers are in transition, perhaps even a funny mirror image of what the Bears could be next year if they go into full rebuild mode. Key losses on offense — a combination of free-agent departures and injuries — have left a once-dangerous power-running ream with a franchise-record-low of 75 yards rushing over two games. The Steelers remain the oldest starting defense in the NFL with an aged secondary seemingly no longer capable of making impact plays.
But they are a proud team with a proud tradition and won't be an easy out on national television two weeks running. The margin of error changes on the road, and mistakes will have to be at a minimum if the Bears are to continue their winning ways.
Special contributor Mike Mulligan co-hosts "The Mully and Hanley Show" weekdays from 5-9 a.m. on WSCR-AM 670.