By Dan Durkin-

(CBS) Both on the field and off the field, it was remarkable to see the effect the zone read attack had when it was unleashed in force during the 2012 NFL season.

Pundits labeled it a gimmick and assigned it a shelf life as it if were a perishable item purchased at the grocery store. Assumptions were made about how quickly defensive coordinators would devise a scheme to thwart it and render it useless. The best arguments for it phasing out revolved around the money that is typically invested in starting quarterbacks. Would teams be willing to consistently expose their expensive commodities to unlegislated hits outside of the pocket?

Judging by Week 1 of the 2014 season, defensive coordinators haven’t figured it out, and teams are still willing to utilize their quarterbacks as running threats.

For years, the NFL was dominated by pocket passers. Strong-armed quarterbacks would stand tall in the pocket and survey the field and wait for receivers to come open down the field. While that style of quarterback remains alive and well today, there’s a burgeoning new breed in the league who are mobile, dual-threats who force the defense to account for the quarterback as a ballcarrier and defend all 11 players on offense.

On paper, zone read is simple to explain: line the quarterback up in the shotgun with the running back offset to his side, put the ball in the running back’s belly (known as the “mesh point”) and read the unblocked backside defensive end. If the end crashes down the line of scrimmage, the quarterback keeps the ball. If the end stays home, he hands the ball off to the back.

For a defense, it’s not so simple.

Given that zone read plays are run from passing formations, reading keys can be a challenge. Bears defensive end Willie Young expounded on what he looks for prior to the snap to help him diagnose the play.

“Down and distance,” Young said.  “Hopefully you can get a few keys from your opponent’s stance, alignments and personnel sometimes. It could be something as small as alignments, someone’s motion, where is the back offset to.”

On Sunday, the Bears’ run defense again struggled to defend zone read and split zone plays, allowing the Bills to rush for 193 yards. Looking ahead to its next four opponents, Chicago expects to see a lot more of zone read until it proves it can defend it.

“You know San Fran is going to come out running that zone read,” Young said of the foe awaiting Sunday.  “I woudn’t be surprised if we get that for the rest of the year. That’s not just singling us out, that’s across the league. Zone read is like, everybody’s buying stock in that particular play right now.”

Football plays happen in a span of seconds. Individual decisions made by players are made in split-seconds, so any misread or misstep can be the difference between a play succeeding or failing.

For a team like the Bears, who run more of a three-wide, one-back spread offense, the defense doesn’t get many live reps against the zone read during practice. In Bourbonnais, the only time the Bears were seen practicing their run fits against zone read was during the end-of-practice walk-through period.

Bears coach Marc Trestman is keenly aware of the threat this scheme presents to a defense and remains optimistic.

“When you’ve got to defend 11, the game changes dramatically on the defensive side of the ball,” Trestman said. “It’s something that we think we’re getting closer to fixing.”

The Bears have had issues defending zone read since the Seattle game in the 2012 season. The age of some of their defenders seems to be manifesting in a variety of areas, one of which is getting back to full speed after a misread. The gash plays the Bills ran off of zone read plays indicate the Bears may not be as close to fixing it as Trestman thinks.

“We just got to continue to work on our rules and guys stay disciplined in their rules,” Trestman said. “There is somebody for the back, there is somebody for the quarterback on each of those plays. A lot of them are based on formations and on demeanor of the back as he works into the line of scrimmage, and we just got to get better at it. We’ve got the guys to fix it. We see the light. Certainly with the amount of read zone we saw (Sunday), there was certain reason to believe it can be fixed. But it’s got to be fixed on every play, we can’t be inconsistent. We’ve got to have consistency in that area, and that’s what we’re going to continue to work to as we move through the season.”

Dan Durkin covers the Bears for CBSChicago.com and is a frequent contributor to 670 The Score. Follow him on Twitter at @djdurkin.