The Bengals are looking for more pass rush from defensive ends Carlos Dunlap and Michael Johnson. (AP Images)

Hardened Bengals defensive coordinator Mike Zimmer stood around a small group of reporters near the entrance to the locker room Wednesday. When a question involving how different the team looks with a persistent pass rush -- noticeably absent in recent weeks -- he nodded and let the question hang in the air for a long six seconds.

“Good observation,” he finally said.

Zimmer rarely went into a second or third sentence for any answer during this tight-lipped session, but certainly didn't need to in regards to this topic. Even the amateur eye could recognize the difference in the Bengals' defense when the front four play to their pass-rushing potential. Without it, they look like a nail without a hammer. They pack no punch.

More precisely, they resemble a team on a four-game losing streak.

Last season, the defensive line became the calling card of the seventh-ranked defense in 2010. The young core of DT Geno Atkins, Michael Johnson, Domata Peko and DE Carlos Dunlap appeared on track to be the Midwest incarnation of the Super Bowl champion Giants. No team showed more the value of how a front four can alter a game in the now pass-heavy NFL than New York.

Four games into the season, the development of the dominant front four hit a lull -- all except unanimous midseason All-Pro DT Atkins and his seven sacks.

Cincinnati had 16 sacks in the first four games of the season (3-1 record) but has seven in the past four (0-4).

“We’ve got to get off the football and go,” Marvin Lewis said. “Those guys continue to progress, but we want it to happen as quick as we can.”

Most in need of pressing fast forward is Dunlap. He set goals to join the elite NFL pass rushers like Jason Pierre-Paul and Osi Umenyiora. What he'd shown between injuries during his first two seasons suggested he was on track.

Instead of making good on a personal milestone to reach 10 sacks this season, he's only managed one in his six games -- he missed the first two weeks after a preseason knee injury.

This isn't how his third season was supposed to play out.

In 2011, Dunlap had more sacks, hits and hurries combined than any other 4-3 defensive end in football during his healthy eight-game stretch to open the year. He suffered a knee injury in preseason this year, but insists it hasn't been an issue. His lack of production has.

Last season, Dunlap had three sacks, 10 hits and 24 hurries at the midway point in the season. This year, he has one sack, seven hits and 10 hurries. 

In the past three games, Dunlap has just three hurries, two QB hits and no sacks facing minimal double teams while Atkins draws plenty of attention inside.

Dunlap's been far from alone in trying to figure out why the group hasn't dominated in sacks like it did last year. It doesn't come with a specific answer.

“There's numerous reasons you can say,” Dunlap said. “Teams know we have the pass-rushing ability that we have and they're doing a good job trying to eliminate or slow us down. And then, obviously it just depends on what the situation is, whether we can pin our ears or not.”

Sunday won't be the easiest time to break out. New York has allowed nine sacks all season. Zimmer knows his defense would look different if Dunlap and company could keep QB Eli Manning on the run but won't be judging this group on the whole if they don't. In fact, defending his talented, young core four elicited his longest response of the day.

“Everything in the NFL is cyclical,” he said. “You don’t play the run good, you start harping on the run. You don’t play the pass good, you start harping on the pass. Everything kind of goes around with how can you improve the areas you need to improve on.

"Some offensive lines are way better than others. They keep more guys in in protection. They use different protections. Let’s just count (sacks) up at the end and see what happens.”

Follow Paul Dehner Jr. for Bengals updates on Twitter at @CBSBengals.