Don't mess with Marquand Manuel during pregame warm-ups. You're liable to catch some heat.

On any given game day, you'll see the 37-year-old with his headphones on, drowning out the noise as he bobs his head to the beat. He'll run a few laps around the stadium with a menacing stare on his face, like an assassin fixated on his next victim.

Folks unfamiliar with the Atlanta Falcons likely would mistake Manuel for a player. His players view him as a guy who will cuss anybody out, make no mistake about it. That's part of the reason why Manuel commands respect as he makes the leap from secondary coach to defensive coordinator, a move made official Friday.

"M, he's a perfectionist," free safety Ricardo Allen said of Manuel. "He knows the ins and outs of every player. He does the studying. He has the passion to lead. He's a natural leader. And people are willing to follow him."

Falcons coach Dan Quinn promoted longtime colleague Marquand Manuel, right, to defensive coordinator. Leslie Plaza Johnson/Icon Sportswire

Manuel is a coach willing to put on cleats, line up opposite his defensive backs and get physical with them off the line. His hands-on approach and aggressive style just might be the added push the Falcons need to elevate an improving defense to yet another level.

Falcons coach Dan Quinn relieved former defensive coordinator Richard Smith of his duties earlier in the week, with Smith now reportedly interviewing to be linebackers coach for the Los Angeles Chargers. Per ESPN's Adam Schefter, Quinn took over playcalling duties from Smith late in the regular season, during a Dec. 4 game against Kansas City. It was about that time Atlanta's defense started to show remarkable improvement, surrendering 21.4 points per game over the final seven, including the playoffs, after allowing 27.6 over the first 12.

Manuel had a hand in the improvement, too. According to multiple sources, Manuel was involved in playcalling involving nickel situations. Maybe it was an audition. Maybe it was just a matter of getting a different coaching perspective. Whatever the case, there's confidence in Manuel's ability to make the defensive calls, even if Quinn, the former defensive coordinator in Seattle, has a heavy hand in it moving forward.

Quinn no doubt will refer to it as a collaborative effort, but Manuel will get ample opportunity to run the defensive show despite no prior coordinating experience. He knows the defense thoroughly, having previously served as the assistant defensive-backs coach under Quinn in Seattle.

Allen wisely declined to discuss anything related to playcalling, but he certainly backed Manuel as his defensive coordinator.

"The players are going to be pushed by him daily, and he's going to push us to another level to be great," Allen said. "I think he's a good person for the job because he'll put the work in."

Manuel will have to deal with scrutiny, of course, but expect him to be unfazed. Folks will bring up the story of him asking then-draft prospect Eli Apple, now with New York Giants, if he liked men during an interview at the NFL combine. Manuel was publicly reprimanded by the organization and required to go through sensitivity training; he apologized for the embarrassment he caused.

If Manuel's defense falters in matchups against Drew Brees, Jameis Winston and Cam Newton next season, he'll certainly hear criticism. But again, it's not his personality to be rattled, no matter the situation.

As with the rest of the Falcons, Manuel will enter the 2017 season with a bad taste in his mouth from the Super Bowl LI implosion in which Atlanta blew a 28-3 lead in a crushing, 34-28 overtime loss to the New England Patriots. But at least Manuel knows he'll have a talented group around him that in 2016 featured NFL sacks leader Vic Beasley Jr., emerging nose tackle Grady Jarrett, rookie standouts Deion Jones and Keanu Neal and Pro Bowl cornerback Desmond Trufant, who will return after missing the season's second half following pectoral surgery. The improved speed on defense, coupled with the presence of Trufant as a shutdown corner, will allow the Falcons to continue the trend of playing more man-to-man defense, as they did successfully later in the season.

Manuel’s ability to get the best out of his players was evident in the way cornerback Jalen Collins made a dramatic leap in his second season as a replacement for Trufant; in the way cornerback Robert Alford shook off problems with penalties to become a playmaker; in the way Brian Poole went from being undrafted to evolving into a reliable nickelback; and in the way Neal and Allen were able to work in unison at the safety spots.

Again, Manuel is all about an aggressive, attacking style. It's in his nature as a former NFL strong safety. That's the mentality and approach you see from him every day in practice. And that's the look you'll see in his eyes every game day.