Steve Atwater chuckles at the memory.

The Broncos’ legendary safety was sitting in the stands watching Peachtree Ridge High School play football. The powerhouse Class 5A team from Suwanee, Ga., included Atwater’s son, Steve Jr., as well as a swift, hard-hitting, play-making cornerback/wide receiver named Bradley Roby, who would go on to become the Broncos’ first-round draft choice in 2014.

“Bradley’s mom, Betty, came to every game. She sat right near us,” Atwater recalled. “She’s very proud of her son, and man, she would talk some noise. She’d be sitting in the stands shouting ‘4-2-8! 4-2-8!’ “

It took Atwater a while before he figured out what Mary Roby was shouting about.

“It was because Bradley ran a 4.28 40-yard dash — in high school, if you can imagine that,” Atwater said. “Betty is very proud of her son. Whenever my wife (Letha) talks to Betty, I always tell her, ‘Say hello to 4-2-8!’ “

During his senior season, Roby was a fixture in the Atwater home.

BRONCOS MAILBAG: Pose a question for Mike Klis

“That’s my best friend, Lil’ Steve,” Roby said. “His dad, Mr. Steve, had a great family atmosphere. He had four kids and a big ol’ mansion. I always loved to go over there. They made me feel like part of the family, and Mr. Steve would always welcome me. (Letha) would always cook for us.

“You have to understand having a single mom is how I grew up. It was nice to see that visual. A lot of times where I am from, with my friends, it was just us and our moms. We don’t get to see that family structure. It was always refreshing to go over there and spend time.”

Roby’s mom, with assistance from the Atwaters, helped lay the groundwork for his future.

The Broncos have seen Roby, the 31st overall pick from Ohio State, develop into an impact rookie cornerback for a revamped defense that’s helped the 11-3 Broncos clinch their fourth consecutive AFC West title. Roby has become Denver’s No. 1 nickel back, and his 60 tackles (59 solo) rank third on the team. He has two interceptions, two fumble recoveries and a sack, making him the first Broncos rookie in 25 years to accomplish that.

“He’s been playing well. Things are starting to slow down a little bit for him,” said Broncos star cornerback Chris Harris Jr. “He’s doing his job. You are going to have ups and downs as a rookie, but the thing about Bradley is that he is able to forget about the bad plays and just bounce back. That’s tough for some rookies, because once they get in the hole, they can’t crawl back out of it. But man, Bradley just pulls himself up and makes the next play.”

Roby got schooled early in training camp, with wide receiver Demaryius Thomas doing the teaching by catching long passes while Roby tried to get his bearings. But even as Roby was getting burned, he impressed.

“He has the courage to make tackles,” said Hall of Fame cornerback Rod Woodson, who was a coaching intern with the Broncos during training camp. “He’s a hard worker who was willing to put in time to get better.”

Those basic skills were there long before Roby wore Ohio State scarlet and gray or Broncos orange and blue.

“When he was in high school, we knew that if he stayed healthy he’d have a good chance of playing in the NFL,” Atwater said. “I don’t throw that around lightly. But he was just so explosive, and he came up with big play after big play.”

Roby had six interceptions, along with 29 receptions for 526 yards as a senior, scoring 11 touchdowns.

Steve Atwater Jr., who went to Peachtree Ridge for his senior year of high school before attending Georgetown University, where he played football, remembers the moment he first glimpsed Roby’s athletic prowess.

“When I first met him, it was right before P.E. class,” Atwater Jr. recalled. “He was wearing jeans and a T-shirt, and he walks over, grabs a basketball and just dunks the mess out of the ball. I was like, ‘Wow! This dude is explosive!’ “

The two remain close, texting almost every day. And “Mr. Steve” chimes in once in a while, too.

“I’ll ask him stuff, little things, to help my game,” Roby said. “He always lets me know he’s there for me.”

Staff writer Troy E. Renck contributed to this story.

Patrick Saunders: psaunders@denverpost.com or twitter.com/psaundersdp

Rookie defensive backs

Nine defensive backs were selected in the first round of the 2014 draft. A look at how they’ve fared:

CB Justin Gilbert

Browns (First round, eighth overall)

Playing time has been sporadic and his performance uneven. The Browns have seen more promise from undrafted corner K’Waun Williams.

CB Kyle Fuller

Bears (14th overall)

Came out of gate fast with two interceptions in first two games, but QBs have picked on him of late. Shows big-play potential but is raw.

S Calvin Pryor

Jets (18th)

A natural run stopper at strong safety, Pryor has been forced to play free safety in the Jets’ struggling secondary. The rookie was benched midway through the season after struggling with his tackling and showing up late for meetings.

S Ha Ha Clinton Dix

Packers (21st)

Began season as a nickel back but now he’s a starter at safety. He’s given up some big plays and whiffed on some tackles, but he’s earned a reputation for big hits.

CB Darqueze Dennard

Bengals (24th)

In August, Cincinnati coach Marvin Lewis called Dennard “the best rookie corner I’ve seen.” That was premature, as the corner has played only 58 snaps.

CB Jason Verrett

Chargers (25th)

Was having an outstanding rookie season until he tore the labrum in his shoulder in late October and was lost for the season.

S Deone Bucannon

Cardinals (27th)

Has been used as a hybrid safety-linebacker, or as the Cardinals call it, a “dollar linebacker.” He’s proving to be a punishing tackler.

S/CB Jimmie Ward

49ers: (30th)

Earned time as San Francisco’s nickel cornerback before going on injured reserve with a foot injury after Week 10.

CB Bradley Roby

Broncos (31st)

A hard-hitting, fast and physical player who’s getting time as a nickel back. He’s the first rookie in 25 years to record two interceptions, two fumble recoveries and a sack in the same season.

Patrick Saunders, The Denver Post