Panthers defensive end Antwan Applewhite remembers getting a look at 6-5, 345-pound defensive tackle Jason Shirley when he joined the practice squad last month and thinking, "My God, that's a big man."

But Shirley has done more than just take up space since he was added to the active roster Dec. 7 following season-ending injuries to starting defensive tackles Sione Fua and Terrell McClain. Shirley, who was cut by Cincinnati and Seattle before the Panthers picked him up, has a sack in each of the three games he's played with Carolina.

Shirley's size might help him stand out. But he is part of a group of unheralded, mostly unrecognizable tackles who have held their own since rookies Fua and McClain went on injured reserve.

The guys they replaced aren't exactly household names, either. Fua and McClain are third-round picks whose reps increased when free agent defensive tackle Ron Edwards tore his biceps at the first practice at training camp.

"I think they've answered the bell pretty well this year," offensive tackle Jordan Gross said of the defensive tackles. "To have a whole roster full of unknown names pretty much outside of this locker room and to see how well they've performed lately has been a testament to who they are."

The Panthers were near the bottom of the league in run defense near midseason. But they have gradually improved to 21st among 32 teams by allowing an average of 95.6 rushing yards over the past five games - a stretch in which the Panthers went 4-1.

The improvement has come despite a defensive interior that includes Frank Kearse, a rookie who was plucked from Miami's practice squad in September, Andre Neblett, a second-year pro who was undrafted out of Temple, and Shirley, whom the Bengals tried to convert into an offensive lineman a couple of years ago.

"Even with a lot of the young guys we've got playing, they've stepped up fast and taken over and done what we needed them to do to win games," Applewhite said. "We've got a lot of young guys inside and they're just going to grow up and get better. For a lot of guys, it's their rookie year, second year, a lot of them haven't played much. So it can only go up from there."

Another young tackle might get a chance to play at New Orleans this week while Neblett recovers from a concussion. Panthers coach Ron Rivera said Ogemdi Nwagbuo, a third-year player who was waived by San Diego in November, would start against the Saints if Neblett is not cleared.

There are a lot of armchair quarterbacks who believe the Panthers should draft a defensive tackle in the first round next year. Rivera is not convinced.

"That's a little bit of a stretch in light of the way guys have played. We've had a number of guys who have stepped up and played well for us," Rivera said. "To me, the tackle position is not really a concern. We'll see. We'll evaluate."

Shirley, 26, the Bengals' fifth-round pick in 2008, said he's not concerned about how the Panthers' front office approaches the draft.

"I don't worry about it, man, because nobody really knows what's going on inside. We had two young guys go down that were doing good, and I got my opportunity," he said. "That's all I was waiting for. Speedy recovery for those guys, but while they're down I'm keeping up the slack. We're not missing a beat."