FLOWERY BRANCH — The Falcons are quick to note that they made 17 player moves over the offseason, but landing defensive coordinator Mike Nolan may be the team’s most important offseason pickup.

Former coordinator Brian VanGorder was in his first stint as a defensive coordinator in the NFL. He returned to the college ranks after last season.

No players in the meeting room will be able to question any calls or scheme adjustments by Nolan because of his experience as a head coach and coordinator. He has coached in the NFL since 1987, was the 49ers’ head coach from 2005-08 and has been the defensive coordinator for six other NFL teams.

The defense, which showed signs of marginal improvement under VanGorder, must make a major leap in pass coverage and on third downs under Nolan. Also, the run defense is now suspect since middle linebacker Curtis Lofton, the team’s leading tackler over the past the seasons, signed with the New Orleans Saints during free agency.

Over the past few weeks during organized team activities and minicamp, which is set to conclude Thursday, Nolan has put names and faces with those little dots he has watched relentlessly during his film analysis of the team.

“After you watch that film, you think they might be bigger or smaller than they are,” Nolan said. “There are some surprises.”

While the unit will not undergo an overhaul, there will be some fundamental changes.

“We’ll be 4-3 and we’ll use 3-4 at times, but we’ll be primarily a 4-3 because this team was built that way,” said Nolan, who is considered a proponent of the 3-4, but has coached both systems. “You want to play to your players’ strengths.”

The defense’s intensity and tempo have been fast-paced during minicamp practices. The defense, under Nolan, clearly plans to attack the opposition.

The new schemes have infused the unit with enthusiastic spirit.

“We are rowdy,” linebacker Sean Weatherspoon said. “You can definitely sense that from [the beginning.] All of these guys are having fun out here. We’ve kind of taken the mentality that it’s our time.”

While Weatherspoon will be expected to improve in his third season, the defensive ends stand to benefit the most from Nolan’s schemes.

“All of those guys, if they were on a 3-4 team, would be outside ’backers,” Nolan said. “They could benefit. I think the inside ’backers could benefit, too. The 3-4 is very friendly to linebackers.”

Nolan was the New York Jets’ defensive coordinator when they drafted John Abraham, the Falcons’ top defensive end, in 2000.

Weatherspoon, who played weakside linebacker last season, doesn’t have much of a learning curve.

“He’s playing the same position in this defense that he was before, so there are no changes there,” Nolan said.

Nolan looks forward to the competition at middle linebacker between Lofa Tatupu and Akeem Dent, who will battle to replace Lofton.

“Akeem is a young player that we’re hoping just continues to mature and get better and better,” Nolan said. “Hopefully, that’s happening. He’s done a real good job out here. Lofa is a dependable guy that’s a veteran who has some pelts on the wall. He’s done an outstanding job.”

The creative Nolan would not rule out both inside linebackers playing at the same time.

“We want to get our best three on the field,” Nolan said. “Hopefully, that’s not because of injury. If somebody beats somebody out, that would be good.”

The addition of cornerback Asante Samuel is expected to boost the pass coverage.

“He’s got great anticipation,” Nolan said.

Nolan is pleased with the play of safeties Thomas DeCoud and William Moore, but doesn’t see much depth at the position.

Nolan warned about getting too excited about the defense’s early showing.

“Right now, we’re just running around in shorts, so everything is high-speed in shorts,” he noted.