Manning, who started the previous two seasons at weakside linebacker, declared early for the NFL draft and was selected in the fifth round by the Green Bay Packers.
"Terrell made the best decision for him and his family and obviously it worked out for him because he is a Green Bay Packer," said Archer. "Obviously the decision that Terrell made was something he felt was in his best interest, and we support that.
"You've got to understand both sides of it. Terrell talked with his family and that was what he decided to do."
D.J. Green's situation wasn't as simple. Green, a 6-foot-4, 214-pound sophomore from Macon, Georgia, started seven games for the Wolfpack in 2011, totaling 28 tackles, one sack, and an interception. In late February Tom O'Brien announced that he had been suspended for the 2012 season by the NCAA for taking a banned substance.
"During the offseason, I wanted to gain weight so I took a supplement that someone from home gave to me," Green said at the time. "I wasn't responsible enough to check with our coaches to make sure that it was something legal and now I'm paying the consequences.
"I apologize to my teammates, my coaches and to all the Wolfpack fans and hope that other players out there learn from my mistake. Even though it breaks my heart that I won't be able to play next year, I will work hard every day in practice to help try to make my teammates better."
"D.J. Green's situation was something that caught us off-guard," said Archer. "It was unfortunate, but you have to move on and learn from it. Hopefully our guys will learn that before you take anything you clear it with our trainer first."
Not only did NC State have to replace seniors Audie Cole and Dwayne Maddox in the spring, but they also had to now replace Green and Manning.
"It was scary," said Archer. "Going into the spring you look at our linebackers and the only guy with any real experience was Sterling Lucas, and he didn't play last year."
Luckily for NC State the Wolfpack retained Jon Tenuta, who was courted by multiple schools in the offseason before choosing to stay in Raleigh and is considered to be one of the top linebacker coaches in the country.
Lucas, who sat out last season with a knee injury, was back at middle linebacker but inexperienced flanked him at weakside and strongside linebacker.
What was Archer looking for from the group as spring practice began?
"We wanted to see progression and development," Archer stated. "Listen, early on they had their struggles, but we put them in the stadium three times, for two scrimmages and the spring game. Now, that first scrimmage, it was scary. There were some breakdowns, and we got gassed a few times.
"But, that is a learning experience. When they are in the stadium we don't coach them. We coach them in practice because when you walk in that stadium you have to make the calls, get lined up, and execute. The first one was rough, but that was to be expected. The second scrimmage we saw improvement and that was encouraging."
After two scrimmages and 15 practices Archer was eager to see how the group would perform in the Kay Yow Spring Game.
"In my opinion, both sets of linebackers were very productive in the spring game," he said. "They played better than they had all spring and that is what you want to see. We needed them to make progress in a tough environment and they did that.
"They had to do it... make their calls and execute and it is what they did. Against Tennessee there will be 82,000 screaming fans and they will need to rely on what they're coached on... be ready to perform."
State returns plenty of experience along the defensive line and might have arguably the most experienced secondary in the country. But, will the linebackers hold up? Mike Archer isn't sure, but he feels a lot better than he did prior to spring practice.
"Coming out of the spring we feel better," he said. "It's going to be interesting to see how they respond against Tennessee on national television when something bad happens. But, they are who we have and we're going to play them. What we expect them to do is get better each and every week and if they do that we'll be fine.
"We will put them back out there in that stadium three or four more times in August, and that is where they will have to learn some more. I do like the progress I've seen so far."