FLOWERY BRANCH — Now a year into his duties, Atlanta Falcons defensive coordinator Mike Nolan is starting to get comfortable with his surroundings as he begins the preparation for his second season with the team.

Does that mean his job is easier? Not at all.

With Atlanta’s organized team activities underway this week, Nolan is faced with the task of building a Falcons defense that features plenty of new faces following key offseason departures.

Some headline names from recent years are gone, with John Abraham, Brent Grimes and Dunta Robinson leading the list. Starting linebackers Stephen Nicholas and Sean Weatherspoon are currently injured, and 2013 first-round draft pick Desmond Trufant hasn’t been able to attend an OTA yet.

But for Nolan, it’s nothing out of the ordinary for this time of the season.

“Every year it’s a new challenge,” Nolan said. “You can compare it to the year before, but the problem is that nowadays you have a new squad. In our case, we’ll have some players doing new things and some young guys coming in and contributing.”

But it’s not as if Atlanta’s defense is receiving a major facelift, especially after going 13-3 during the regular season last year and finishing one game short of a Super Bowl appearance.

Instead, it’s simply taking a shape that best fits this year’s new personnel. And a full year with the Falcons has given Nolan more knowledge of the best way to make it all work.

“Having been here a year, there’s no question that it helps,” Nolan said. “You can identify guys a bit better, as far as what they can and cannot do.”

Some of the new faces don’t need much work to identify their abilities.

That doesn’t ring much truer than with recent addition Osi Umenyiora, who replaced Abraham as Atlanta’s primary pass rusher at defensive end.

Umenyiora signed with a two-year, $8.55 million deal with the Falcons in March, providing nine years of NFL service complete with 75 sacks. After spending his entire career with the New York Giants, he looks to mount a comeback in Atlanta after recording just six sacks last season.

Nolan says Umenyiora is performing at a high level during OTAs, as expected, but he’s been most impressed with how quickly the veteran has taken on a leader mentality with his new teammates.

“He’s an early bird kind of guy, but some of younger guys — and a couple of our older guys — have kind of gravitated toward that, and they’re all working out together,” Nolan said. “From an impact standing, we know what he’s done on the field, everybody can see that and I’m aware of that too. But the little things are appreciated, and I think they’ll help us.”

It’s what Umenyiora has come to expect out of himself as a player with nearly a decade of experience under his belt. Now the Falcons’ go-to option for pressuring the quarterback, Umenyiora will be relied on to fill the void left by Abraham's departure.

Abraham tallied a respectable 10 sacks last season, but the Falcons ranked 25th in the NFL with only 28 as a team.

For now, Umenyiora is letting his play do most of the talking with his new teammates.

“As the guys get to know me better and better, I’ll become more and more vocal,” Umenyiora said. “I’m just out here doing my job, doing what the coaches ask me to do. The leadership aspect will take place later on.”

He joins a line that includes veterans Jonathan Babineaux and Kroy Biermann, who combined for 7.5 sacks last year.

Biermann’s numbers could be a little different this year, though. At 6-foot-3 and 255 pounds, Nolan intends to use him as “hybrid” player capable of lining up in the three-point stance, but also quick enough to duck into pass coverage.

Nolan is looking for more players that could serve a similar role, specifically among his younger group.

“What I’ll be looking for is if one or two of these new guys on the roster shows that they might make the team, versatility might be helpful,” Nolan said. “But I couldn’t do tell you who those guys are today.”

The personnel shake-ups are just as dramatic in the secondary, particularly at the cornerback position.

The Falcons were so concerned with their depth at corner that they used their first two picks in the 2013 draft to bolster the position. Trufant was selected 22nd overall out of Washington, followed by Southeastern Louisiana defensive back Robert Alford in the second round.

Alford has been present and impressive at OTAs, but Trufant hasn’t made an appearance since the team’s rookie mini-camp earlier this month. The Washington standout needed to complete one more class this summer before arriving in Flowery Branch to join the team.

Head coach Mike Smith expects a setback for Trufant on the field, but the cornerback should have no issues with knowledge of the playbook. The team has communicated daily with him via Skype and other various means of technology, filling him in on the defense to get him up to speed.

“He’s getting the mental part ... it’s just the physical part and the bonding part of being here with the rest of his teammates (that he’s missing),” Smith said. “Desmond has been here for the rookie mini-camp. And he comes from a line of football players, so he knows what it’s all about.”

The defensive changes have left Smith and his staff with plenty of work to do before training camp begins, but he says the pieces are mostly in place.

But as with all NFL defenses conducting OTAs, changes are nearly a certainty.

“This is the time of the year that we recalibrate our roster,” Smith said. “We start that recalibration at the end of the season, and we’re pretty much finished with it. That’s not to say we’ll always be finished with it — you’re always trying to get better at any point in time in the year.

“These guys are becoming a team, and this is going to be our team for the 2013.”