Washington defensive coordinator Greg Manusky, left, talks with defensive tackle Phil Taylor (99), center, and defensive end Jonathan Allen (95) during Friday’s practice. (Photo by John McDonnell / The Washington Post)

RICHMOND — A few years back, Trent Williams attended a football game at Stone Bridge High School, located in Ashburn just a short distance from the Redskins’ facilities. Washington’s left tackle was there to watch his nephew, but another player on the team left Williams so impressed that he went back to team headquarters the next day and told teammates they had to come with him the next week.

A couple of players took Williams up on the invitation, and by the end of the game, they were all tweeting about this surefire NFL prospect named Jonathan Allen.

“Jonathan was unbelievable,” Williams, whose nephew Tylon Lynch now plays for Oklahoma, recalled after Monday morning’s walk-through at Redskins training camp. “It was obvious that he was a man among boys.”

Little did Williams know that five years later, after a stellar college career at Alabama, Allen would be walking off the same training camp practice field as him.

Things unfolded better than the Redskins could have imagined in April’s NFL draft, when Allen — regarded by many analysts and NFL talent evaluators (Washington’s included) as a top-five pick — fell into their laps at 17th overall. Some teams worried about a possibly lingering shoulder injury, while others decided to make a run at offensive players and address the defensive line position later. But the Redskins were delighted to land the local kid, which thrilled Allen and his family on draft weekend.

The smiles and other shows of joy have dissipated for Allen — not because he’s unhappy, but because he’s all business. Allen has absorbed scheme and technique knowledge from his coaches, which he has then translated to the field.

Four practices into his first NFL training camp, Allen hasn’t over-the-top wowed anyone with a series of standout plays. But he has impressed teammates and coaches alike with his steady improvement, his strength, athleticism, maturity and flashes of future greatness.

“He’s still a rookie and has a bunch to learn,” said guard Arie Kouandjio, a former Alabama teammate. “But once in a while, you will see him do stuff that somebody else can’t do and you’re like, ‘Wow, that’s pretty good.’”

Soon after he arrived, the Redskins understood Allen was different.

Jonathan Allen was the No. 17 overall pick in the 2017 NFL draft. (Photo by Doug Kapustin/For The Washington Post)

It’s not uncommon for an NFL rookie to arrive on the scene fresh off a dominant college career, but look very much like a rookie once he is standing next to the veterans. Maybe a lineman needs to add more mass to his frame, or trade some doughiness for a more chiseled physique.

But Allen proved the exception. Sure, he’d like to get a little bigger. But already he boasts an NFL-ready body. He has a broad, thick chest, arms bigger than some people’s thighs, and tree-trunk legs.

“His body,” Williams takes a deep breath and shakes his head. “He looks like he’s been here before.”

Psychologically, rookies often either show up with one of two demeanors: overly confident, or completely wide-eyed and overwhelmed.

But not Allen. It’s all business with this kid, teammates and coaches say. He punches in, gets to work. He shows no emotion following successes or missteps.

“He doesn’t say a lot. Very strong. Very strong, and wants to work, which is good,” Coach Jay Gruden said. “He’s put on a lot of muscle mass already in the short time that he’s been here, we feel like, and he’s going to get stronger and stronger. I like his work ethic, I like the way he learns and the way he works. He’s really mature. Really, really mature.”

After practicing alongside Allen in the spring and then spending the bulk of the offseason working out with him, ninth-year veteran Ziggy Hood says Allen was born for football. Hood, Gruden, Kouandjio and Williams all attribute Allen’s maturity and fundamental polish to the foundation laid at Alabama. Coach Nick Saban’s program preaches hard work, accountability and dedication to team above self.

“At Alabama, we’re just part of one big team. Everybody wants to play for the team and win for the team,” Kouandjio explains. “We go through a lot of attention and big games and stuff like that. I’m not surprised he’s not super overwhelmed.”

Allen is indeed a young man of few words, but he is quick to credit Hood for his transition from college to the NFL. He spent the summer weeks in between offseason practices and training camp working out with Hood. Allen learned how to better take care of his body and how to further push himself.

He started the summer pushing 365 pounds on the sled, but after lifting and training daily with Hood, he now can push 405 pounds.

“He’s one of the hardest workers I’ve ever seen,” Allen said of Hood. “So just trying to keep up with him has really pushed me in my break. … My main focus is just giving 100 percent effort and the rest will come later.”

Allen’s college foundation has shown on the field as well, and the tutelage of defensive line coach Jim Tomsula has only further equipped the rookie for early success.

“He’s compact. He has a good fire off the ball and stays low,” Williams said. “He keeps his hands in the right place, and he’s strong. … Strong as an ox. That in and of itself makes him a handful on every down. … He’s definitely going to be a Pro Bowl player once the game slows down for him. I don’t know if it’ll take all of training camp, or just two weeks. But when it does, we’re all going to reap the benefits.

“I watched him dominate high school kids, watched him dominate at Alabama,” Williams continued, “and now he’s my teammate, so it’s a little weird. But I expect him to come here and dominate, too.”

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