USC’s running game has lacked explosiveness

USC’s passing attack has thrived as quarterback Matt Barkley and receiver Robert Woods break or flirt with records seemingly every game.

But what of the running game?

USC ranks 71st among 120 major-college teams, averaging 136.6 yards a game.

“It’s just been very up and down,” Coach Lane Kiffin said Monday. “Not near enough explosive plays.”

USC has passed for 14 touchdowns and rushed for four.

Marc Tyler is entrenched as the starter, but the coaching staff has not settled on a consistent complement.

And at a school popularly known as Tailback U, the Trojans lack a breakaway threat. USC’s longest touchdown run is 10 yards.

That’s why an already crowded backfield swelled more with the addition of speedy freshman George Farmer, who has been converted from receiver and is listed for the first time on the depth chart at tailback.

Tyler is averaging 4.7 yards per carry. Curtis McNeal, aided by long gains against Syracuse and Arizona, is averaging 8.5 yards, D.J. Morgan 3.3.

Coaches have given Dillon Baxter only nine carries. Freshman Amir Carlisle had two before suffering an ankle injury against Arizona State.

Kiffin longs for the Thunder and Lightning days of LenDale White and Reggie Bush, one of the most productive tandems in college football history.

He said he was “frustrated” by the inability to find a workable combination. “We didn’t want a system where there’s a new guy every week, where we’re looking at a guy for something,” he said. “We want it like it was before. For whatever reason, we can’t get it to that point.”

Kiffin is aiming for better balance when the Trojans play California on Thursday night at AT&T Park in San Francisco.

“We can’t do that all year long,” he said of USC’s pass-heavy approach. “We’ll get exposed if we keep trying to do that.”

Tyler ready

Tyler said his body benefited from last week’s open date and he is looking forward to playing for the first time at AT&T Park.

The senior was not allowed to participate in the 2009 Emerald Bowl because of too many “negative points” related to class attendance.

Tyler rushed for 79 yards and a touchdown in seven carries last season in USC’s 48-14 victory over Cal.

Recognizing the Golden Bears’ varied defensive fronts, Tyler said, is the greatest challenge. “It’s not hard for me because I’ve been here forever,” he said. “It could be hard for some people.”

Kiffin said Tyler finally appears to be up to speed after sitting out training camp because of a suspension. The coach referred to the loss against Arizona State, when Tyler fumbled in the second half.

“There [are] two or three runs — if he’s fresh, if he’s in great shape — that are touchdowns,” Kiffin said.

Quick hits

Carlisle, cornerback Torin Harris (shoulder) and linebacker Lamar Dawson (ankle) are listed as possible for the Cal game. … USC is 63-30-5 against Cal. The Trojans have won seven straight in the series and nine of the last 10.

gary.klein@latimes.com

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