A former defensive coordinator at the University of Florida, Michigan and Notre Dame, Mattison, 59, first met the Ravens' head coach as an assistant on the Western Michigan staff of Harbaugh's father, Jack Harbaugh. Mattison has nearly 40 years of coaching experienced and helped develop 18 future NFL players during his 11 years as a college defensive coordinator before making the jump to the NFL at Harbaugh's urging last spring.
After Mattison coached one year in the NFL this past season for the NFL's second-ranked defense, Harbaugh became convinced he should tab him as Rex Ryan's replacement over three other internal candidates: Vic Fangio, secondary coach Chuck Pagano and defensive line coach Clarence Brooks.
"Greg is a guy that I have full trust and belief in, and not just because of his track record," Harbaugh said. "He's been successful at every stop, but the job he did this year with our guys, I think he established himself as a premier coach in the NFL. If you talk to our players, they'll tell you the same thing.
"Rex did a tremendous job of getting the most out of his players, having them believe and trust what they're doing and to be accountable for what they're doing. Those are the strengths that I've always felt Greg had as a coach."
Meanwhile, Harbaugh promoted special-teams coordinator Jerry Rosburg to assistant head coach and Fangio from special assistant to linebackers coach.
An imposing coach with a booming voice, Mattison has no intentions of changing much about the Ravens' relentless defense that helped Baltimore engineer a dramatic turnaround from 2007 to finish 13-6 this year and advance to the AFC title game.
Last season, Mattison worked primarily with star middle linebacker Ray Lewis and inside linebacker Bart Scott as both recorded over 100 tackles apiece.
"I believe very strongly in that you have to be aggressive," Mattison said "You have to be an attacking defense. Obviously, that's been the M.O. of the defense here for years. In looking at what we do defensively, we don't plan on changing a great deal. It's not broken by any means.
"It's all about the chemistry and the players believing it's their defense. That won't change one bit. My job as a defensive coordinator is to keep that going and keep them knowing what it takes to play at that level and keep them believing it's their defense."
Mattison began coaching at the high school level in 1971 prior to stints as an assistant coach at Illinois, Cornell, Northwestern, Navy, Texas A&M before running defenses at high-profile college programs in Ann Arbor, Mich., South Bend, Ind., and Gainesville, Fla.
Harbaugh has known Mattison since 1984 when they worked together at Western Michigan under Jack Harbaugh.
"Those are the kind of things in football that are so meaningful," Harbaugh said. "Those were those bonds that are built. We have those bonds throughout our coaching staff, and that's another reason why I think this is such a strong, strong move."
Besides the molding influence of Jack Harbaugh, Mattison credited his development from a wide range of coaches from Lloyd Carr, Gary Moeller, Bob Davie, Ty Willingham, Urban Meyer and Bob Blackman.
For several years, Mattison had turned down opportunities to coach in the NFL before Harbaugh talked him into making the jump last spring after winning a minor bidding war with the Florida Gators.
If it hadn't been Harbaugh on the telephone recruiting him, Mattison probably would have opted to stay at Florida.
"I wouldn't be here today if John Harbaugh wasn't the head football coach," Mattison said. "A big part of that was I had complete confidence in what he was going to do and how he was going to do it. So, I made the move from college to professional football because of him.
"I really believed in my heart that he was going to do what it took. That kind of trust is what makes you as an assistant try to do everything you can to help him be successful and help the program be successful."
Not sure what to expect in his first pro football coaching experience, Mattison found himself thrilled with Lewis and other players' maturity and work ethic as he made a smooth transition from coaching 18-year-olds to grown men.
"I guess the biggest thing is they are men and they're professionals," Mattison said. "In college, you have to bring a person from being an infant, teach them how to step, teach them where to place his hands, every little part of being a good football player, where in the professional level they already know that.
"And your job here is to get them to do something that makes them even better, whether that's mental, whether that's psychological, whether that's technique. The thing I found out real quick is that these guys are like the best players you've ever had at the college level all in one. And that was kind of a fun thing to learn."
The Ravens conducted four interviews for the job, holding internal discussions about the merits of respective external candidates before deciding that there was no valid reason to look elsewhere.
"We've got guys in the room that the players know, they trust, they believe in," Harbaugh said. "Why start over in that sense? That was the thinking as far as staying inside. Everyone of them said no matter which one of us gets it, we'll be in full support of the coordinator and we'll work together."
Logistically, the Ravens will continue to run a 3-4 alignment as their base defense with a scheme predicated by its strength and versatility in the front seven with several players capable of playing more than one position. There will continue to be occasional 4-3 elements, according to Mattison.
Mattison intends to study every defensive call from each snap last season to analyze why each decision was made to try to derive as much knowledge as possible about what were the most effective strategies.
"One thing we will do in the next year, we're going to keep the package the same," Mattison said. "There are too many good things in that, but we're also going to really study closely to make sure we're getting our best players in the best position for them to have success."
With former outside linebackers coach Mike Pettine now with the New York Jets as Ryan's defensive coordinator, Fangio will be responsible for coaching the outside and inside linebackers. Harbaugh added that Mattison will remain involved with the linebackers in drills and meetings working in conjunction with a quality control coach.
"How that sets up, that still remains to be determined," Harbaugh said of giving Fangio assistance with the linebackers. "We'll have to figure that out, but it will work well."
Fangio will continue to be responsible for special assignments in terms of scouting opponents' tendencies, a behind-the-scenes role that he excelled at last season as a special assistant to Harbaugh.
Since the Ravens' inaugural season in Baltimore in 1996, every defensive coordinator has eventually become an NFL head coach, including Marvin Lewis, Mike Nolan and Ryan in addition to former defensive assistants Mike Smith and Jack Del Rio.
Now, Mattison has large shoes to fill with Ryan's departure to coach the Jets. During Ryan's four seasons, the Ravens never finished lower than sixth in the NFL in total defense.
Mattison's elevation continues the Ravens' tradition of promoting from within for defensive coordinator.
"I never have looked ahead," Mattison said. "I've never been one of those guys that said, 'At this age, I want to be here. After this job, I want t o do this.' Fortunately, there have been opportunities where you have to make a decision, but I've always been one of those guys who felt that your job is to do the best job you can to make these players be the best players they can be.
"I've never had a dream that, 'Boy, some day I want to be a head football coach in the NFL.' I don't know that when I first started coaching 37 years ago, I ever said to myself, 'Boy, I can't wait to be a coordinator in the NFL.' .. I'm very humbled and very proud to be named the coordinator of the Ravens. It's a very exciting time."
Mattison had just one request before any second-guessing and Monday morning quarterbacking begins in earnest.
He doesn't want his NFL debut as a defensive coordinator to be judged by the fast-and-loose affair that tends to go on at the NFL's annual Pro Bowl in Hawaii.
"Please don't evaluate the coaching staff by the Pro Bowl," Mattison said with a laugh. "I've just been told we can run two defenses total, and they don't really play hard all the time."
Aaron Wilson covers the Baltimore Ravens for the Carroll County Times and the Annapolis Capital.
Mattison tabbed as defensive coordinator
Ravens Insider Top Stories
2017 Baltimore Ravens Team OutlookSenior Fantasy Football Expert Shawn Childs goes in-depth covering every Fantasy aspect of the 2017 Baltimore Ravens!
Daily Dr. Roto: Way-Too-Early WR TalkThe season is still months away, but even senior expert Dr. Roto knows it is NEVER too early to start the Fantasy Football conversation.
Scout FantasyFriday at 8:02 AM
2019 Intro: Hoover WR George PickensJACKSONVILLE, Ala. -- Earlier this month, Scout saw George Pickens in action for the first time. The rising junior football prospect may be one of the best in Alabama's deep 2019…
Scout FootballThursday at 6:32 AM
90-man roster analysis: CornerbackThe Cardinals lost starter Marcus Cooper to free agency, and now it appears the team will move forward with a competition between Justin Bethel and Brandon Williams for a starting…
CardinalsSourceWednesday at 7:14 AM