HOUSTON — The man many believe to be the greatest quarterback of all time is marching into NRG Stadium for his seventh Super Bowl appearance Sunday, a game many expect to be a coronation of Tom Brady's brilliance.

An Atlanta Falcons defense full of guys who were in elementary school when Brady won his first Super Bowl is standing in his way. 

Under Dan Quinn, the Falcons have aggressively remade their defense over the past two seasons, spending their first- and second-round picks in both drafts on that side of the ball. 

What Quinn has built so far is not as dominant as the defenses of his days as Seattle Seahawks defensive coordinator. Full of first- and second-year players, Atlanta finished 25th in the NFL in total defense, 27th in scoring. 

But the Falcons have been much better down the stretch, channeling Seattle's ferocious energy into a unit that has forced timely turnovers and limited five of their past six opponents to 21 points or fewer — the exception being the Saints — as the offense rolled up points left and right.

All of those young defenders have been the catalyst for Atlanta's run to Super Bowl LI. And other than brilliant pass rusher Vic Beasley, no Falcons additions have loomed larger than two former LSU stars who took very different paths to the starting lineup.

Worth the wait

One round after Atlanta selected Beasley in 2015, Jalen Collins looked like the perfect fit at 6-foot-2, blessed with the long, rangy frame that served as Quinn's blueprint for cornerbacks in Seattle.

Things started to go awry right away. Collins missed summer workouts with a Jones fracture in his foot, and there were still remnants of the maturity issues that flared up at LSU, where he lost his starting job as a sophomore.

"Came in last year, was injured, threw him in the fire, and like any rookie does, he had a lot of off-the-field things," Atlanta secondary coach Marquand Manuel said. "A lot of maturity factors that he had to handle in the offseason."

Instead of playing a key role, Collins was an afterthought, starting just two games and contributing a paltry 17 tackles.

"It's always tough, going through troubles in your first year when you think you should be playing, doing this or doing that, and it's probably not going the way you think it should," Collins said.

Manuel saw a different Collins last spring. Humbled by the struggles of his rookie year, he worked hard in the offseason, showing up early and displaying a maturity he hadn't in his first year.

Then came the setback: Collins was suspended for the first four games of the season after a violation of the NFL's policy against performance-enhancing drugs. Redemption would have to wait a little longer.

"He was hurting because of those four games that he missed, and he came and he told us that he owes us," Falcons safety Ricardo Allen said. "We don't take it like that. People make mistakes and we know that — we're all humans — but the way he came back, he stepped up and worked at it."

Nobody knew it at the time, but Atlanta would need Collins badly for its Super Bowl run. 

Pro Bowl cornerback Desmond Trufant suffered a season-ending pectoral tear in early November, robbing the Falcons of their best defender.

Collins had to start and, all of a sudden, the physical tools Atlanta had seen became evident on the field. Collins broke up 10 passes, picked off two more and then made the biggest play of the NFC title game, stripping Packers fullback Aaron Ripkowski in the red zone for the turnover that allowed Atlanta's offense to bury Green Bay.

"He's a great athlete, plays hard, can play the ball well," Trufant said. "Great, great ball skills and plays with a lot of confidence." 

Sudden impact

Tempered expectations met Atlanta's decision to spend its second-round pick on Deion Jones this season.

Few people could see Atlanta's vision. Jones had impressive speed and athletic ability, to be sure, but most analysts expected him to be a developmental player on the weakside given his lack of size and his role at LSU.

Quinn and general manager Thomas Dimitroff saw an intelligent player who might be able to handle the defense's most cerebral role: wearing the communicator and relaying calls to the rest of the unit.

"Although he only started one year at LSU, he had plenty of experience," Quinn said. "We knew he could run, and we knew the hit factor was there and then, could we get all the rules down for him?"

Atlanta had resources waiting.

As young as the starting lineup is, the Falcons have veterans on the roster, and the linebacking corps included veterans Paul Worrilow and Sean Weatherspoon — both productive players who have worn the communicator at some point in their careers.

"(Worrilow has) been in my ear since Day 1, helping out, grooming me into the person I am today," Jones said. "Worrilow is mostly like playbook, technique, stuff like that. Weatherspoon is more the energy, my voice."

Jones hadn't handled the communication alone at LSU. According to Jones, it was more of a collaborative system of calls, and obviously the Tigers had NFL players Kwon Alexander and Lamin Barrow during his time there.

Atlanta was asking him to be the flash point for the defense.

"To wear the indicator as he is, you've got to have a voice," Worrilow said. "Even if it isn't comfortable, you have to learn to lead the group and be loud."

Unlike Collins, Jones made an impact right away. Blindingly fast for a linebacker, he was a weapon in coverage right from the start, and he showed his physicality when he stonewalled Cam Newton at the goal line in the fourth game of the year.

Being the communicator took a little more work.

"My voice has changed," he said. "Being louder, being more vocal. From the bye week (after the 10th game of the season), watching all the games we played, realizing where I could have helped out, could have said something that helped us out, and I took that to my game after that."

Worrilow and Weatherspoon, who opened the season as the starter next to Jones, saw their protégé come into his own down the stretch. By the time the season ended, Jones was a legitimate contender for defensive Rookie of the Year, having posted 108 tackles, 11 pass breakups and three interceptions, two of which he returned for touchdowns.

"He ain't a rookie no more," Weatherspoon said. "When I was starting with Deion ... I've been doing this seven years, (and) I didn't have the communicator. Deion had the communicator, and I'm telling you, he's really stepped into that leadership role, and he's played exceptional as well."

One last challenge

The ultimate test remains.

Brady awaiting in the Super Bowl, with two weeks for coach Bill Belichick to prepare and both Collins and Jones expected to play key roles. Collins will be under fire at cornerback, and Jones will likely have to play a key role in keeping jitterbug back Dion Lewis from taking over the way he did against Pittsburgh in the AFC title game.

Both players have said all the right things this week.

"Tom Brady is a great quarterback but, as far as emotions go, just trying to treat it as any other game," Collins said. "He is somebody that I'm playing against, not somebody that I'm watching on TV as a fan."

That's the attitude Atlanta has counted on all season. 

On a defense this young, there's no time to be wide-eyed — not in a Super Bowl against a modern-day dynasty.

"It used to be a man's game, but there's a lot of boys playing now," Manuel said. "You've got to make the turn from a boy into a man."

Jones and Collins are boys no more.

Follow Joel A. Erickson on Twitter, @JoelAErickson.