"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 in a statement. "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."
Green, who had started seven games for the Wolfpack in 2011, totaling 28 tackles, one sack, and an interception, was able to practice with the team but couldn't participate in games, leaving a hole at outside linebacker.
"Whenever I got down about it I would hit up coach [Edmond], and we would go work out," said Green. "Every morning before practice I would do my own workout and then come out here and practice.
"The guys out here just made it fun for me and the coaches stayed by my side too. It went well."
What Green did do was try to turn it into a positive. A safety when he arrived on campus in 2010, Green played the position as a true freshman before moving to linebacker in the spring of 2011.
He says that he spent a lot of last year working on the mental aspect of playing linebacker.
"That's exactly what I did. I used my vision to learn when I couldn't play," Green added. "I studied film, watched practices. I learned to see things that I couldn't see when I was on the field. For me that was big because I was new to the position.
"Overall I feel like I just matured. I had to open my eyes to see who was really there... get my priorities in order and basically just take care of business."
Now Green is eligible and ready to impact.
"It felt great getting back here knowing I'll be playing," he said. "I had a lot of weight come off my shoulders. It feels great to be back."
The 6-foot-4, 228-pounder has been named by multiple coaches as a potential leader for the Pack's defense this season.
"I do feel like that's going to be my role... being a leader," he said. "If you're going to be a leader you have to be one that everybody respects. I'm not going to be yelling all the time. I can relate to all my teammates and they can relate to me. That's comfortable."
There has also been some change for Green. NC State has a new coaching staff which means he has a new position coach, Dave Huxtable. An experienced linebackers coach, Huxtable is also the Pack's defensive coordinator.
"He's a good guy," said Green. "I know on the field he's amped up. Off the field he calms it down a little bit, but I know he had just as much passion coaching as I have playing the game."
The biggest change for Green has been on the field. He's previously played outside linebacker the past two seasons, but he is now starting at middle linebacker for the Wolfpack.
"I feel like I expected [the position change]," said Green. "I've never played middle before... used to playing outside, but I'm learning to train my eyes. I've had some one-on-one meetings with coach Huxtable that have been great. He's helping me a lot with that... using my eyes more. I'm beginning to pick it up for sure."
As of now, Green is working at middle linebacker with juniors Brandon Pittman and Rodman Noel lining up outside of him. While the group doesn't have a lot of starts under their belts, all three have terrific size and athleticism.
In fact, Green has high hopes for the entire defense.
"I'm excited about the group myself," said Green. "We're all really big and fast. It's not going to be easy playing sideline-to-sideline against us.
"I like the front four we have. Our safeties will come up and hit you, and I like how our corners play on the outside. I'm excited about our defense."
What about the 2013 season?
"It's not going to be a wasted year," said Green. "I know this coaching staff wants to win just as much as we do.
"We came to college to win ball games, and they really stress that to us. That's what I love about them.