The Arizona State backfield isn't exactly loaded with experience.

Sophomore Cameron Marshall is the leading returning rusher from a season ago (294 yards), and the other running backs vying for time during fall camp have a combined three carries at the collegiate level.

Speed, though, has a way of quickly making up for shortcomings, and despite the group's inexperience, running backs coach Bryce Erickson is optimistic about his talented unit's potential in ASU's new quick-strike offense.

In addition to Marshall, sophomores Jamal Miles and James Morrison and freshmen Deantre Lewis and Kyle Middlebrooks have shown flashes of promise that have their position coach licking his chops.

"We haven't really had a problem figuring out a way to get all those guys … involved in our offense," Erickson said. "That's a real good problem to have. Each and every one of those running backs bring something different to the table."

After missing much of the spring with hamstring injury, Marshall has so far looked solid in camp, showing particular improvement in his hands.

The San Jose, Calif., native said he has worked on improving his flexibility in effort to stay out of the injury report this fall.

"I'm feeling better than ever," Marshall said. "That was the biggest thing for me, to get rid of all those little aches, that flexibility is going to help me the most."

While Marshall has become more limber, Morrison has become leaner.

The former walk-on out of St. Mary's dedicated his offseason to tightening up his physique and shedding pounds. The results have been evident.

"He's one of the hardest working players we have on this football team," Erickson said. "It's that old cliché, what you put into is what you get out of it. The hard work that he put in in the offseason is definitely shown so far. I'm really proud of him."

Lewis has been a quick learner, seemingly collecting a firm grasp on the offense despite having just three official practices under his belt.

A 2,400-yard rusher during his senior season at Norco High in Norco, Calif., Lewis said he spent a good deal of his time this summer studying his playbook, an effort that has helped him catch on quickly to offensive coordinator Noel Mazzone's new offense.

"I'm just trying to go through the motions and understand how the defense flows, how the offensive lineman flow with me," Lewis said. "I've just got to keep working on stretching the play and I should be good."

Erickson likes the versatility he sees in the freshman.

"Deantre is a little mixture of both [speed and power]," the running backs coach said. "He's a 205-pound running back who has the quickness Jamal [Miles] has, and he can be a physical, powerful runner."

The runnings backs had their best performance of camp thus far during Friday's 7-on-7 drills, with each back dicing through the defense or getting the edge for sizable gains.

While the defense is winning a majority of the battles early in camp, continuing to back up its claims as one of the nation's best units, the Sun Devil running backs -- who head coach Dennis Erickson called the fastest he's had at ASU -- are illustrating a talent gap that is closing between the two sides of the ball.

And with so much talent, yet so little experience, in the backfield, the competition at that position has elevated the play of those searching for time there. A number of players have split time with the first-string unit, and the players said they know taking a day off isn't an option if they want to win a job.

"It gets us motivated a lot," Lewis said of the tight competition. "Depending on who starts, it means they are a step ahead and the backups have to work harder in order to play. That's all it is - big competition. That's what we want."

Day 3 of fall camp, which featured players in shells (shoulder pads and helmets) got testy toward the end of practice, when two fights that involved a majority of the team broke out. The second skirmish resulted in running for the whole team before practice was cut a few minutes short.

The war of words didn't end when the tussle did, though, with members of the defense shouting "D side" as they ran.

Dennis Erickson likes the passion as the competition between the offense and the defense elevates early in camp.

"They're competitive against each other," the coach said. "After your third day you're a little tired, a little irritable … That's kind of football when you have stuff like that."

Junior wide receivers Gerell Robinson and Aaron Pflugrad missed Friday's practice with hamstring soreness, though Erickson said neither injury was serious.

"If we had to play a game tomorrow they could probably play," Erickson said. "But there's no sense in taking any chances with them. The same with Vontaze [Burfict] and his ankle."

Burfict missed his second straight practice with a sprained ankle suffered before Thursday's practice.

Mo Latu, a 6-foot-3, 306 pound two-way line prospect out of Perry High in Gilbert, attended ASU practice on Friday. Latu, a senior ranked as the No. 5 center prospect nationally and No. 7 recruit in Arizona, has been offered a scholarship by the Sun Devils.