Juwan Thompson was different from the other little kids. He wasn’t tall, but he was stocky, with big arms and shoulders much too wide for a 5-year-old.

“His babysitter called him ‘Little Hulk,’ ” recalled Thompson’s mom, Ramona Griggie. “So ever since Juwan was little, we’ve called him our ‘Incredible Little Hulk.’ “

The Hulk’s not so little anymore.

The Broncos’ rookie running back is a 5-foot-11, 225-pound block of granite. The Duke graduate’s combination of physical power, maturity and intelligence has made him one of the surprise contributors on a talented Broncos team now considered the favorite in the AFC to return to the Super Bowl.

Though Thompson’s carries have been limited, he has been an effective special-teams player and has produced when called upon after No. 1 running back Montee Ball suffered a strained groin during Denver’s Week 5 victory over Arizona. Thompson, used primarily as a short-yardage back in the Broncos’ victory against San Diego on Thursday, had 24 yards on seven carries, including two touchdown runs.

“Juwan’s special. I’m not at all surprised he’s made it with the Broncos,” Duke coach David Cutcliffe said. “Of all of the running backs I’ve coached, I’d say he was the most intelligent. He was so aware of everything we did on offense. He was so prepared, so mature.”

Which, of course, made him a perfect fit to be part of quarterback Peyton Manning’s backfield. Cutcliffe, who was Manning’s offensive coordinator at Tennessee and remains one of the quarterback’s closest confidants in football, urged the Broncos to sign Thompson after he was passed over in the draft.

“I talked to (offensive coordinator) Adam Gase, (general manager) John Elway and Peyton,” Cut cliffe said. “I told them that Juwan would be a good fit. He’s smart, he’s tough and he’s great in pass protection.”

An honors student at Woodward Academy (a prestigious prep school in Atlanta), Thompson graduated from Duke with a major in sociology and a minor in education. He had already been accepted to graduate school at Duke and was planning to become a coaching assistant after being bypassed in the NFL draft. Then the Broncos called. He made the team after an impressive training camp.

“It was an easy decision,” Elway said.

Thompson’s forte is his versatility. In Cutcliffe’s wide-open, share-the-wealth offense, Thompson was one of six players to have at least 60 carries last season. None of those Blue Devils had more than 113 carries.

In a game against Virginia Tech, Duke used Thompson as a linebacker to shadow quarterback Logan Thomas. Thompson made three tackles in six plays.

“We had seen what he could do on special teams, we knew he could tackle, so we gave him a shot,” Cutcliffe said.

Thompson was born in the U.S. Virgin Islands. His mom moved him to the Atlanta area when he was not quite a year old. His grandmother, Mary Thompson, still lives in the Virgin Islands and follows every Broncos game anyway she can.

“Juwan is huge in the Virgin Islands — the biggest thing since Tim Duncan,” Griggie said with a laugh, referring to the San Antonio Spurs’ star power forward who was born and raised on the island of St. Croix.

Thompson’s mom gushes with enthusiasm when she talks about her son.

“He hated missing school. He always wanted perfect attendance,” she said. “He was a cool kid, but a smart cool kid. And always polite and respectful.”

Cutcliffe echoed those sentiments, but added a caveat.

“Juwan never fell into trash talking on the field,” he said. “But he would hear what was said. He paid attention. On special teams, I could seem him change directions to take on a certain guy. He knew how to send a message.”

In other words, for all his gentlemanly ways, you don’t want to make the Little Hulk angry.

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

Thompson snapshot

• Born in U.S. Virgin Islands

• Loved playing basketball growing up. Could dunk by the eighth grade and was a 200-pound, 3-point shooter by his sophomore year at Woodward Academy in Atlanta.

• Began focusing on football as a junior. Ran for 1,622 yards and 22 touchdowns as a senior, earning honorable mention all-state honors.

• Was courted by 25 colleges, including Stanford, but chose Duke.

• Finished his four-year college career with 24 starts, 1,244 yards rushing and 56 receptions.

• Signed with the Broncos as an undrafted free agent and made the team with a strong preseason (29 rushes, 143 yards) and as a force on special teams.

Patrick Saunders, The Denver Post