USC looks to turn its fortunes around in the turnover department

Four weeks into the season, USC’s defensive backs have a number seared into their minds.

“Twenty-nine,” Olaijah Griffin said.

That represents the number of pass breakups by the Trojans this season, tops in the nation. But there’s a problem. USC hasn’t turned any into interceptions. Top-10 teams Alabama and Stanford, for instance, have 28 pass breakups but also have seven and five interceptions, respectively.

“We’re not going to think about the negative parts about it,” said Griffin, a true freshman cornerback who is expected to get more playing time Saturday at Arizona. “We know we are getting our hands on the ball. Now we just need to execute and make plays.”

The Trojans have forced only two turnovers, one on the first defensive play of the season when Isaiah Pola-Mao popped the ball loose against Nevada Las Vegas and Porter Gustin recovered it. Essentially, USC has played nearly four full games since then while creating only one turnover, a fumble recovery in the third quarter against Texas.

For a defense known for its attacking style under coordinator Clancy Pendergast, this comes as a shock.

“Well believe me, we talk about it a lot,” Pendergast said. “Maybe we’re trying too hard. A lot of times over my career, the turnovers kind of come in bunches, and so hopefully sometime soon that will start falling in our favor. It’s definitely something that we’re not happy about. We haven’t caused enough turnovers.”

Coach Clay Helton said part of the issue is inherent in the Trojans’ playing man-to-man coverage on the outside.

“You don’t see a ton of picks in man-to-man coverage,” Helton said. “You see a lot more in zones. We do have a lot of pass breakups. Hopefully we’ll get our hands on the ball just a little bit more, and it also comes with tipped balls, batted balls. We had a couple the other day that got straight up in the air and felt like they were there forever. We just didn’t come down with it.”

Gustin was informed this week that the Trojans lead the nation in pass breakups.

“Really?” he said. “Well, we need one of those batted balls to land in one of our player’s arms.”

He laughed.

“It’s surprising,” he said. “I think that they’ll come, and when they do, they’ll come in bunches. I think it’s just bad luck. They’ll come.”

On Thursday, as he does every week, Helton gave the defense what he calls the opposition’s “Turnover DNA.”

“What guys are loose with the ball, what you should be targeting,” Helton said. “I’m ready for a wave of turnovers.”

Cornerback movement

Last week, Washington State had amazing success throwing the ball to the side of the field occupied by either Isaiah Langley or Greg Johnson.

The Cougars’ Easop Winston Jr. caught six passes for 143 yards and two touchdowns while exclusively lining up against Langley and Johnson. On the other side, Iman Marshall shut down Washington State’s leading receiver, Tay Martin, who was limited to one yard.

This week, Griffin has been playing more snaps with the first-team defense. Helton said Thursday that Langley would get the start at Arizona but that Griffin would get plenty of snaps behind him.

“We’ve been splitting at that left corner position, about 50% of the reps,” Helton said.

Johnson will now back up Marshall.

Gustin avoids targeting

Helton said he had a conversation with Gustin this week about a helmet-to-helmet hit on Washington State quarterback Gardner Minshew that, fortunately for the Trojans, was not called targeting on the field or after being reviewed by the Pac-12 office.

“I didn’t notice it in the game,” Helton said, “and really didn’t notice it until I got the chance to watch the tape. Even Porter did not know it had happened until he watched it on tape. It was not intentional by him. He’s a bull in a china shop. We’ve got to try to aim just a little bit lower.”

Gustin sat out the second half of the Texas game and the first half of the Washington State game because he had been ejected for a targeting call.

brady.mccollough@latimes.com

Twitter: @BradyMcCollough