"That was the big issue with him," said Rick Badanjek, the Glen Mills running backs coach. "He was very immature. As time went on, he blossomed. But it wasn't an easy road for him."
Somehow that road led the Ardmore native to all the right places. In 2009, Temple made the freshman its featured back. This season, despite being Ray Rice's backup, the Ravens' third-round pick has become one of the NFL's most accomplished rookies.
Next Sunday, of course, the road will land the 22-year-old in Super Bowl XLVII as Baltimore opposes the San Francisco 49ers on sports' ultimate stage.
It's a journey that would have been unlikely without the swift and thorough transformation Pierce underwent at Glen Mills, the picturesque, 187-year-old facility for troubled boys.
"Bernard grew into a man here," said Kevin Owens, Glen Mills' coach. "By the time he left we all believed he could do something special. But the Super Bowl? As a rookie? I don't know if we thought that big."
Pierce's initial reaction to Glen Mills - a "Why-am-I-here-and-when-can-I-go?" attitude - wasn't unusual. Most of the teenagers who politely greet visitors to the sprawling rural campus were just as scared and disoriented.
"It's no easy adjustment," said Owens, a 29-year school employee. "They feel like, 'I'm coming to a school for juvenile delinquents. I've got to be a tough guy.' We don't allow that here. We create a culture where everyone can feel comfortable and learn to be a normal kid."
Before they helped mold his speed and muscle into rare football talent, Owens, Badanjek, and the Glen Mills staff had to rework his attitude.
Raised by his mother and grandmother in a working-class island on the Main Line - his estranged father died in a 2008 auto accident - Pierce exhibited a rebelliousness that was exacerbated by a group of friends he now calls "knuckleheads."
"I can't talk specifically about why he was here, but there are kids here who are worse and better than Bernard," Owens said. "He wasn't hard-core. He was a likable kid who made bad decisions.
"We're not a prep school. We're a school for juvenile delinquents. I always tell these kids, 'You've got to be willing to let the streets go.' With the help of everyone here, Bernard did."
Both coaches said Pierce's turning point came after his junior year. At that point, his sentence completed, he could have returned to Lower Merion. Instead, he asked to stay. And because his GPA and credit total met the school's standards, he was allowed to do so.
"There have been very few times when we have a kid stay more than one year," Owens said. "When we asked him why, he said, 'I'm making changes. I want to get my life together.' He could have gone back, been around the girls, had more fun. But I think he realized the potential was there for him to fall back [into trouble]."
Pierce's mother, Tammy, said that because of the problems he'd encountered there, she wouldn't have allowed him to return to Lower Merion.
"My son wasn't always an angel there and I understand that," she said. "But he wasn't guilty of everything people there said about him, either. If he was, he'd probably have gone to prison, not Glen Mills."
Tammy Pierce became an outspoken advocate and vigilant watchdog for her son at Glen Mills.
"One time she wanted to take him home," Owens recalled with a chuckle. "I had to tell her, 'He's not going anywhere. He's mine now.' We had lots of those conversations. But she came to see that we genuinely cared for him, that we made sure he was in the right classes and working to get the ACT scores he needed. After a while, she was like any other mother who wants the best for her kid."
Far less reshaping was required on Glen Mills' state-of-the-art playing fields.
Pierce immediately became a track standout. By senior year, his 100-meters time of 10.6 seconds was Pennsylvania's best for 2009. He also starred on the power-lifting team, adding strength and bulk in the process.
Owens and Badanjek were working with another group of Glen Mills students when they spotted Pierce and decided to shepherd him.
"We wanted to pull him over to our unit so we could watch him, mentor him, help him whenever we could," Badanjek said. "We gave him an opportunity and he took full advantage."
In his two football seasons there, the 6-foot-1, 210-pound Pierce ran for more than 3,200 yards, performed satisfactorily in the classroom, and, despite his reserved nature, served in the Bulls Club, the student government.
"I got in a little trouble," Pierce said last week about his journey. "It's in the past. I was going in the wrong direction, making mistakes, teenage stuff. I made a [complete] turn."
That turn attracted the interest of several Division I coaches. None was more enchanted than Temple assistant Mark D'Onofrio, now the University of Miami's defensive coordinator.
"Coach D'Onofrio slept here, I think," Owens said. "He was here at all his track meets, all his games. I'd see him and ask what he was doing here and he'd just say, 'I'm here to see my man.' I think that's why Bernard chose Temple. They did their work."
The Temple staff contacted a lot of people at Glen Mills, down to the custodians, then-Temple coach Al Golden said.
"What we found out was that Bernard learned how to be a man, and how to make better decisions," Golden said in 2009. "We heard a lot of the same things, that Bernard was a good kid who made a mistake. We were willing to give him a chance here, because we felt he made a decision not to go down the path he seemed to be heading. We don't sugarcoat things around here. He and his family understood the kind of support he'd get from our staff and Temple. We trusted that he was changed. He trusted in us."
After a season of spelling Rice successfully, Pierce burst into the spotlight last week, when he collected 52 yards on nine carries in Baltimore's AFC championship game upset of New England. For the year, he averaged 5.2 yards and accumulated 443 rushing yards.
"We don't miss anything when he's in the game," Rice said last week. "We're two different running styles, but we both get the job done."
According to Owens, Pierce will be the second Glen Mills graduate to play in a Super Bowl. John Jones, a Ravens tight end, got there in 2001.
"It's awesome for me to see where he is now," Owens said. "He has a child, a girlfriend. He's taking care of the things he needs to. He's a good person."
Contact staff writer Frank Fitzpatrick at email@example.com. Follow on Twitter @philafitz on Twitter.