All around him, Joe Cullen sees potential.

Cullen, entering his second season as the Jaguars' defensive line coach, said what means more than that now is fulfilling that potential, of taking another step toward becoming a consistently effective unit.  Cullen said he sees a real chance to do that this season.

There are reasons for that, Cullen said – and Aaron Kampman is just one of them.

Just as crucial, he said, are depth and development.

"There are certain things you have to do a little better," Cullen said recently when discussing the line for this story for jaguars.com. "You have to keep working at it. The finish wasn't quite there. We have to finish a little better as a group, but I think the group will really take another step forward this year."

The Jaguars, after ranking a well-publicized last in the NFL with 14 sacks in 2009, improved that area in Cullen's first season.

The team signed Kampman as a high-profile free agent, and selected defensive tackle Tyson Alualu with the No. 10 overall selection in the NFL Draft. Their presence, and a group of young, improving linemen, helped the Jaguars register 26 sacks – still 30th in the NFL, but up 12 from the previous year.

To Cullen, an important number within those numbers is 20.5.

That's the number of sacks from the defensive line in 2010, a statistic in which the Jaguars improved from 32nd in 2009 to 13th last season. Oakland led the NFL in the area with 28, and Chicago had 25 with Indianapolis finishing with 24.

"You look at the 4-3 teams in terms of those at the top, we're close," Cullen said, "but we're not there. We have to take another step this year."

Cullen said that's possible, and said a big reason is the presence of Kampman, a veteran end signed from the Green Bay Packers during the 2010 off-season.

"We have a great veteran in Aaron Kampman," Cullen said. "He gave us great leadership on and off the field – and great play. We expect him back healthy."

The Jaguars signed Kampman not only for on-field production, but for off-field leadership. He registered four sacks in the first eight games of the season, a number Cullen said easily could have been higher, then sustained a torn anterior cruciate ligament that ended his season.

"He was having a great year up until the injury," Cullen said. "He had four sacks, but when we looked at this tape, he could have had eight sacks at the break. Getting Kamp back fully healthy will be huge taking the next step."

Also key is the continued development of Alualu, considered a surprise selection by some as a Top 10 selection in 2010, but a player who Cullen said excelled as a rookie.

"He's only going to get better," Cullen said. "He did some great things as a rookie. He really showed some signs of rushing the passer."

Cullen said one key element for young players along the defensive line is the ability to beat offensive linemen one on one. From that raw, physical attribute a base can be built, and skills can be developed toward becoming an elite-level player.

Alualu showed that attribute as a rookie, which Cullen said could bode well for not only Alualu but the entire defensive line group.

"That's critical, and he showed some good run-stuffing ability," Cullen said. "I think he's only going to get better."

Alualu, who started 16 games as a rookie despite several injury issues, finished the season with 3.5 sacks, and Cullen said he should only improve as a pass-rusher.

"We expect him to come back and get that much better from his rookie year to his sophomore year," Cullen said. "At times, he really showed he was that guy. There was some inconsistency in there as well, but I think he definitely has the raw things you look for in that guy, in the under tackle, the three technique. He gets a lot of the one on ones, and I think teams will have to account for him in their protection schemes."

Such a player makes players around him better, Cullen said.

"If they're focusing on that piston that drives the engine – the under tackle in a 4-3 scheme – now some of the ends are going to be left one on one, or maybe the nose tackle is going to be left one on one," Cullen said. "It's going to free up some guys to have one-on-one opportunities."

Cullen said it was evident immediately that Alualu had the tools to be a player around which a line could be built.

"What you look for, No. 1, is a guy who has a great motor," Cullen said. "He has that. He commands respect by what he does on the field – not by his mouth talking, but by what he does on the field. He's a man of few words, but when he does speak, they'll listen. He does it all, by his action, by his commitment. He's a great team guy. You can see it in the locker room. They respect him."

Cullen said he also saw improvement in 2010 from defensive tackle Terrence Knighton, who registered a sack and a half and 45 tackles as a rookie in 2009 and four sacks and four passes defensed last season. Knighton at times last season played at a dominant level, and Cullen said he "showed some rush skills."

"He can be as good as he wants to be," Cullen said. "If he keeps his weight in that 330-to-335 range, he can be as dominating a tackle as there is in the league."

Cullen said a key to the line is getting solid play from starters and reserves. In that vein, he said the continued development of not only second-year veteran tackle D'Anthony Smith – who missed his rookie season with an Achilles injury – but second-year veteran tackle Nate Collins and fourth-year tackle Leger Douzable is critical.

"We're looking for him to do some great things," Cullen said of Smith. "He's back fully healthy, so we're excited to see him."

The Jaguars on paper are less certain at the end position, with Austen Lane starting nine games last season and fifth-year veteran Jeremy Mincey – "he did some great things," Cullen said -- starting eight games after Kampman's injury.  Lane moved into the starting lineup to replace Derrick Harvey, a first-round selection in the 2008 NFL Draft who started 16 games in 2009, but who has just eight sacks in three seasons.

"I think he'll make some improvement in his pass rush," Cullen said of Lane. "He was close a lot, and didn't finish. I think with some added weight he's going to be a real solid left end who can play every down."

Cullen noted that Harvey is still young, and could still develop, and said as a group, there is potential for the young ends to emerge as a solid pass-rushing unit, with rookie end Larry Hart and second-year linebacker Aaron Morgan showing signs of developing as rushers.

"It's a good group to work with, no question," Cullen said.  "The young guys will have another year under their belt, learning and knowing what a full NFL season is. They have that quality you look for, that athleticism."

Cullen said there were times last season when the Jaguars put enough pressure on quarterbacks to alter games. That, as much as sacks, is what matters for a defensive line, particularly one such as the Jaguars that wants to be known as a pass-rushing line. Cullen said the key now is to continue improving and developing consistency, something he said he believes can happen with the current group.

"There were games (last season) we definitely felt like we affected the quarterback," Cullen said. "We did it against Dallas with a four-man rush and didn't have to blitz. We had four picks, two sacks and a number of hits. Against Cleveland, we had six (sacks). There were definitely games we affected the quarterback – a, by sacking him; and b, by getting him off the spot. Sacks will come when you finish better. The rush and the coverage go together. That has to work together, and it did at times last year. You'd like to get the numbers in sacks, and more importantly, you want that quarterback to know he can't stand in the pocket. I felt we made strides last year in those two areas.

"The more we learn, the longer we're on the system. It's one thing to be a good rush front, but to be a good rush front, all four have to work together.

"I think that's what we have to do, and we have to take another step."