Palo Alto grad Keller Chryst will get his chance as Stanford's starting quarterback. Cardinal football coach David Shaw announced the decision to start Chryst on Tuesday at his weekly press conference. Stanford plays at Arizona at 8 p.m. Saturday.

"He has a strong arm, he's accurate and he's athletic," Shaw said. "He's improved a lot, learned and grown from his mistakes. The fact that we need to score more points and need consistency is all fact of it."

Chryst threw for 2,672 yards and 28 touchdowns as a senior at Paly in 2013. He was 149-of-242 passing and averaged 242.9 yards a game.

In three years, Chryst guided the Vikings to a 24-12 record and threw for 7,326 yards and 84 touchdowns.

He'll replace senior Ryan Burns, who went 4-3 (2-3 Pac-12) in his seven starts. Burns completed nearly 63 percent of his passes for 1,058 yards and five touchdowns. He's also thrown seven interceptions.

"I hate to get to this point," Shaw said. "But it's the best thing for this offense. We need more production at that position. It's our challenge to support Keller."

Burns led the Cardinal to wins over Kansas State, Southern California and UCLA to open the season but has struggled ever since, averaging 11 points in Stanford's last four games, punctuated by Saturday's 10-5 loss to Colorado.

"It can't just be about the quarterback," Shaw said. "We need to help Keller be more effective. We need to be able to score points with this personnel. Ryan is as an improved football player over a calendar as I've had. He accomplished a lot in half a year" the game-winning drive at UCLA, as rare road road win at Notre Dame."

Chryst, the son of former 49ers' offensive coordinator Geep Chryst, has appeared in 10 games over the past two years, throwing for 122 yards on 12-of-27 passing. He's thrown for one touchdown and one interception.

"I've been working with both all year and they're both great people," Cardinal receiver Trent Irwin said. "Sometimes you just need a change. We'll see where it goes and have fun with it."

Stanford ranks last in the Pac-12 in scoring (17.0) and total offense (299.1). The offense has scored just 10 touchdowns all year, fewer than Washington's John Ross and Arizona State's Kalen Ballage, the conference co-leaders with 11 touchdowns.

"Both quarterbacks are good," Stanford safety Zach Hoffpauir said. "Maybe it does stimulate the offense a little bit."

NOTES: CB Elijah Holder will miss the rest of the season due to an unspecified injury. ... OL David Bright and Johnny Caspers are questionable. ... FB Daniel Marx is out "but trending upward," Shaw said. ... RBs Christian McCaffrey and Bryce Love are both healthy.