USC’s Sam Darnold isn’t yet a track star, but his recent rushes have helped his passing

USC tracks its players with a GPS system, so after the last three games, quarterback Sam Darnold has made sure to look up an unusual stat. He has looked for his maximum speed.

Darnold reached 18 mph with one run against Arizona State three games ago. “Sam is showing people he’s a lot faster than people give him credit for,” offensive coordinator Tee Martin said.

Reporters began asking Darnold about his newfound quickness. Every time, he instinctively laughed — though Darnold can move well, he’s not known for top-end speed. But on Saturday, he reached another peak.

“I was kidding with him today,” coach Clay Helton said Tuesday. Darnold, Helton said, “got up to 19.3 miles an hour on the GPS system. He said, ‘That’s about as fast as I’ve run since high school.’ ”

Darnold has dazzled in his last six games with his arm, throwing for an average of 302 yards per game with a total of 15 touchdowns and three interceptions. His surge as a passer has happened at the same time as — and maybe because of — an increasing willingness to run the ball.

Darnold’s running statistics remain modest, partially because his rushing figures have been depressed by sacks. But he has made big plays with his legs. On Saturday, he became the third USC quarterback since 2000 to have a 300-yard passing and 30-yard rushing game. Matt Barkley and Carson Palmer also did it once.

On the speedy run against Arizona State, Darnold set a career high with a 39-yard scramble. Against Colorado, he scored on a 24-yard scramble, when he displayed enough speed to peel away from a safety.

“I saw a little opening and based on where the safety was I knew that he wasn’t going to have an angle to be able to get to me, so I decided to make that cut,” Darnold said.

The 19.3-mph dash is a respectable figure, especially for a quarterback. The NFL has more available data on top-end speed. The fastest ball carrier in the NFL this season was Leonard Fournette, who ran 22.05 mph. No quarterback cracked the top 20, meaning they ran 20.81 mph or slower.

Martin and Darnold attributed the running to more man-to-man coverage, which gives Darnold more space if he can get past the pass rush.

But it also underlies a tendency of Darnold’s. Usually, he throws only as well as he moves.

“I thought he made some great decisions in really the last six games using his legs,” Helton said.

He said Darnold’s decreased interception totals were a result of avoiding forced throws. Instead, Helton said, he’s often just tucked the ball and run.

USC stays put in rankings

USC remained at No. 11 in the latest College Football Playoff rankings released Tuesday. USC was one of two teams to not move up or down.

USC moved ahead of Washington and Texas Christian after both teams lost but was jumped by Ohio State, which defeated Michigan State 48-3, and Penn State, which defeated Rutgers 35-6.

Kirby Hocutt, the committee’s chairman, said the committee had extensive discussions about teams ranked No. 7 through 11, and said they teams were very close to one another.

That includes No. 7 Georgia, No. 8 Notre Dame, No. 9 Ohio State, No. 10 Penn State and No. 11 USC.

In three playoff-era seasons, no two-loss team has made the playoff. But this has been a season of unusual parity. It is the fewest number of undefeated or one-loss teams at this point in the year.

UT for Tee?

Martin was the last quarterback to lead Tennessee to a national championship.

Now Tennessee has a coaching vacancy after firing Butch Jones on Sunday. Brady Hoke has taken over as interim coach. Would Martin be interested in the position?

“I look forward to UCLA on Saturday night,” he said. “I look forward to that.”

Martin issued a more straightforward answer when asked if he’d been contacted by the school.

“I haven’t been contacted,” he said. “And I’m really focusing on UCLA.”

Quick hits

Defensive end Rasheem Green (shoulder injury), outside linebacker Uchenna Nwosu (sprained ankle), tight end Tyler Petite (sprained shoulder) and kicker Chase McGrath (groin injury) did not practice Tuesday. “Expecting all of them to be ready by Saturday,” Helton said. … Cornerback Iman Marshall, who traveled to Colorado but did not play for the third game in a row with a sprained knee, was a limited participant in practice. “I think he’s going to contribute in this game,” Helton said. “We’ve been really cautious obviously with a knee, and he’s getting to where you see in practice, you can see the confidence that is coming back.”

zach.helfand@latimes.com

Follow Zach Helfand on Twitter @zhelfand