UNIVERSITY PARK — As Penn State players broke apart, with each position group heading its own way to take part in its own drills this spring, Bill O’Brien made a split-second decision.

Wide receiver Bill Belton started to trot off with his fellow wide-outs and O’Brien piped up.

“Where are you going?” O’Brien asked Belton.

“I’m a receiver,” Belton responded.

“No you’re not,” O’Brien replied, having noticed Belton’s body type — a muscular 5-foot-10 that affords him a lower center of gravity — qualities O’Brien looks for in his running backs.

And so began Belton’s career as a Penn State tailback.

“We put him at running back and then he showed us he has really good feet,” O’Brien said. “He’s got a unique ability to be able to balance, put his hand on the ground and balance himself and spin. He’s done a much better job — knock on wood — in the first three days of ball security. He has really good hands out of the backfield. So I feel good about Billy.”

Belton entered the team’s training camp as the top option at tailback despite not playing the position since his youth football days in Sicklerville, N.J. Penn State’s previous returning rushing leader, Silas Redd, who transferred to USC last week, prompting Belton’s ascension to the starting spot.

Listed at 202 pounds on Penn State’s current roster, Belton slimmed down a tad from his playing weight of 206 last season and believes he will be able to handle hefty workloads if asked to do so.

“Without a doubt,” Belton said when asked if he would feel comfortable carrying the ball between 20 and 25 times per game. “The weight room guys do a good job with us and they’ve prepared us all summer and all spring and I’ll definitely be ready for that.”

As a true freshman last season, Belton contributed toward the end of the campaign operating as a running quarterback out of the Wildcat formation.

He returned kicks occasionally and saw the bulk of his action in the TicketCity Bowl against Houston.

Belton wouldn’t reveal if O’Brien’s offense will feature a similar Wildcat scheme, but said his aims thus far have been to become a complete back.

His favorite NFL running back is LeSean McCoy and Belton said he often watches the Eagles’ rusher to try and mimic some of McCoy’s tendencies.

“I just like his running style, his shiftiness, his catching out of the backfield,” Belton said. “He does a lot of things well and I like to watch him and pick up little tips from him.”

Belton and his fellow backs — senior Derek Day and junior Curtis Dukes, who will likely figure into the team’s running back rotation — have been learning from a new coach following Galen Hall’s departure with the majority of the former coaching staff.

Charles London is the team’s new running backs boss and has brought a different approach to coaching the position than what Penn State players were used to with Hall.

While Hall was an accomplished running back during his playing career and his years of coaching at multiple levels lent themselves heavily to Hall’s teachings, London’s relative youth has allowed him to relate better to his players. London is more hands-on, too.

London’s high-octane coaching style was on display Thursday as running backs went through drill after drill with London either ripping at the football clutched in their arms or swatting at it with baseball bats wrapped in foam.

“I try to take interest in their lives beyond football. About academically and what’s happening with their family life and things of that sort,” London said. “I just try to interact with them a lot. Football can be a grind at times. We try to have some fun in the meetings and I let these guys know, I might be old but I’m not that much older than they are so they make fun of me all the time about that.”

While London played running back in college, he was also a vaunted sprinter at Duke.

With a couple of years on his top pupil, could London beat Belton, one of the Lions’ fastest players, in a foot race?

“If I was the same age as Belton right now, I’d get him. But right now, he’d get me,” London said. “There’s no doubt about it.”

Speed is Belton’s obvious quality. In the spring and summer he’s been striving to improve his blocking and catching the football out of the backfield.

Day, currently the No. 2 running back on the team’s depth chart, brings speed as well and vision.

Primarily a special teams player throughout his career, Day said he hopes to use the experience he gained playing on kickoff and kick return teams in the offensive backfield.

“It’s an important role. It gets you game experience,” Day said of playing special teams. “Truthfully, the special teams plays are a little bit faster than offense. You don’t have the time to set up and read the defenses and things like that. Just the speed and the physicality of it helps a lot.”

At 5-foot-9 and 193 pounds, Day has added five pounds of muscle to his frame in the offseason.

Day isn’t the only Penn State running back to gain size during the spring and summer months.

Dukes checked into training camp at 245 pounds, up from 237 last season. While Day said he hopes to bring physicality to the position group, Dukes doesn’t even have to try. It comes naturally to the hard-nosed, downhill runner.

“With me and Bill, it’s like thunder and lightning,” Dukes said. “He’s more quick and I’m more of the power guy so that’s how we can contribute and help this team more.”

But Dukes finds himself lower on the depth chart after missing spring practice sessions due to academic issues. On Thursday, Dukes admitted he feels like he’s playing catchup.

Dukes said he’s at the point where he’s comfortable with the majority of O’Brien’s plays and offensive philosophy, but still is learning all the protection schemes.

“This is spring practice for him basically,” London said. “This is Day 3 of spring practice for him. He’s still learning the terminology. Everything’s new to him. The pro-style attack — we’re working with him to try and get him up to speed. He’s had a good start and for him it’s going to be key when the pads go on.”

The Nittany Lions’ youthful backfield picked up another candidate with the addition of freshman Akeel Lynch.

O’Brien said he is pleased with the mix of backfield talent and depth.

“(Strength coach Craig Fitzgerald) got (Belton) ready to take the pounding in the Big Ten, but we have other backs that we think can helps us, too,” O’Brien said. “Derek Day, Dukes has shown some good things early in preseason camp and Akeel Lynch, the freshman, is going to be a decent player.

“So we’ve got a lot of guy back there.”