Running back rotation has vexed USC

Ronald Jones II isn’t sure what it is.

“Could be the dreads,” said the closed-cropped Jones ruefully, as he stood outside USC’s locker room on Friday night in Utah.

All Jones knows is that he can’t seem to find open space.

Last season, when the then-dreadlocked Jones broke USC’s freshman rushing record, he ran for 987 yards, scored eight touchdowns and averaged 6.5 yards per carry. He became just the second USC freshman to lead the team in rushing, despite taking less than 11 carries per game on average.

This season, he is averaging less than 31 yards per game. On Friday, he had his worst performance yet, with the exception an injury-shortened game against Utah State. He took eight carries for just 15 yards.

“I’m in a little bit of a slump right now,” Jones said. “The rest of the offense is doing their part, the O-line and everything. I’ve just got to get going.

“I’m just not seeing the field right now.”

Jones’ struggles are the most visible sign of USC’s inability to figure out a proper rotation at running back. Against Utah, USC fed Justin Davis in the first half — he ran for 102 yards on six carries.

Then, USC opted to used Jones more heavily, and gave one second-half series to Aca’Cedric Ware. Neither carved the Utes as thoroughly as Davis, but Davis received just four carries in the last 30 minutes.

Offensive coordinator Tee Martin said he had no regrets.

“We have a rotation, and we trust our backs,” he said.

Coach Clay Helton explained that the redistribution of carries in the second half was partially a result of scarcity. USC had the ball just three times in the half, plus a one-play Hail Mary attempt in the final seconds.

Helton said that the offense is in a bind. It wants to unlock Jones. But doing so means taking away from Davis.

“It’s a catch-22,” he said. “If you leave Justin Davis in, I’ll be getting calls about why wasn’t Ronald Jones in. We have tremendous trust in Ro Jo to be able to do the job just like we have trust in J.D.”

Maintaining motivation

After Friday’s game, Davis said he couldn’t remember the last time USC (1-3) had started as poorly as it has this season.

He wondered how the team would respond.

Helton said he has been pleased with the Trojans’ resilience.

“This is a team that has no quit in themselves,” he said on a teleconference with reporters on Saturday. “I talked to some kids after the game, and all of them were like, ‘Coach, we’re getting there, we’re so close, let’s keep going.’ I thought there were a lot of positives. Last night was a step forward. I don’t look at it as a step back.”

Quick hits

Cornerback Adoree’ Jackson played sparingly on offense against Utah and took just one carry for 11 yards. Helton said he’d planned to use Jackson for six offensive plays, but the offense was moving the ball without him. … Helton said the defense used more substitutions against Utah than it has all season. … USC will resume practice Tuesday.

zach.helfand@latimes.com

Follow Zach Helfand on Twitter @zhelfand