GREEN BAY, Wis. -- Mike Pettine is here to rebuild -- both the Green Bay Packers defense and himself.

Two years after he was fired as Cleveland Browns head coach, the 51-year-old has returned to the game. He was introduced Wednesday as the new Packers defensive coordinator, a job he actually began two weeks ago.

Pettine had been out of coaching in any official capacity for two seasons, although he worked as a consultant for the Seattle Seahawks last year.

“I came out of it and I was just beat up physically, mentally,” Pettine said at his introductory news conference.

The same could be said of a Packers defense that’s been beset with injuries and performance breakdowns in recent years. It led to coach Mike McCarthy’s decision to fire Dom Capers after nine years as coordinator.

Like Capers, Pettine comes in as a former NFL head coach. For Pettine, however, it’s a matter of been there, done that; he is not in Green Bay as a stop on the way to another head coaching job.

“It’s not,” he said. “When I was the head coach, I didn’t enjoy the lack of interaction with the actual football part of it. I always made the comparison, it was going from being the teacher to now you’re the principal. The administrative part might be, as a coordinator, 90 percent football, 10 percent administrative stuff. That essentially flipped, and I didn’t like it.

“I missed the camaraderie of the room, the interaction with the staff, the interaction with the players. The chess-game part of it, the designing a game plan tailored to your opponent."

So no designs on becoming a head coach again? "That’s the furthest thing from my mind," said Pettine. "I’m here to coordinate an outstanding defense and win a Super Bowl.”

Pettine went 10-22 in his two seasons as Browns head coach. Before that, he spent one year as Doug Marrone’s defensive coordinator with the Bills -- a defense that ranked 10th in the NFL. The four years before that, he was Rex Ryan’s coordinator with the Jets, where the defense never ranked lower than eighth.

“His attention to detail is outstanding,” said Marrone, now the Jaguars coach. “He’s very smart. He’s really good in front of the room. Really has the ability to communicate and really put players in great position. It doesn’t surprise me that he’s back in right now. It doesn’t surprise that he’s a defensive coordinator, and it won’t surprise me later on down the road if he’s a head coach again.”

Pettine took the podium Wednesday for his first meeting with the media with a stern, serious look on his face. Yes, he can bring a tough-guy attitude when necessary, but he also takes a modern, cerebral approach to the game.

“I’ve been told my natural resting gaze is not a pleasant one, but there’s not much I can do about that,” he said. “I blame my parents for that. ... I’ve heard that. I think it’s important that the players see the certain way but they understand, too, the thinking that goes behind it. I always like to explain the why.”

Pettine’s task in Green Bay is to rebuild a defense that finished 22nd last season -- the seventh straight year it finished outside the top 10. Breakdowns in communication proved just as problematic as injuries and missed tackles.

In an effort to streamline the process, McCarthy and Pettine put together a defensive staff with new positions like pass-game coordinator (former Packers cornerbacks coach Joe Whitt) and run-game coordinator (former Giants and Patriots assistant Patrick Graham). Whitt also interviewed for Pettine’s job but instead settled for a new title.

Although McCarthy had no previous connection to Pettine other than sharing the same agent, Trace Armstrong, he said the two instantly connected. “It’s important in the game of football, particularly in coaching, you look for people that kind of view the game the way that you do,” McCarthy said. “His background in analytics, the ability to teach and being in tune with today’s athlete, there’s a number of things. I had five clear components and characteristics that I was looking for in the new defensive coordinator. And I’ll say this, Joe Whitt did an outstanding job in his interview. I thought Joe hit the target on the five components. I’m not going to get into specifics to that, but I thought Mike really knocked it out of the park. I knew early in the process that he was the right man for the job.”

Pettine’s scheme has been called complicated by some, and that wouldn’t seem to bode well for a defense that had trouble getting on the same page under Capers. But the new coordinator insisted that’s not the case.

“We like to appear multiple without necessarily putting that much stuff in,” Pettine said. “So, it’s not a system that is overwhelming to learn. The league has changed. When I first got in the league, it was easy to put in 50 or 60 defenses up for a game. Now, you’re 20-25. Why? Because a lot of time you’re dealing with young players that haven’t been veteran guys in a system that know it, and also you’re dealing with the new CBA where you have limited time to get with them, especially in the offseason, for them to learn that foundation. I think as a coach you have to adjust. But no, you look at us, you’re going to see we’re going to be multiple and we’re going to be aggressive.”

ESPN’s Michael DiRocco contributed to this report.