STANFORD, Calif. -- The final test for K.J. Costello came in the pregame warmups. If he could show he could hold and throw the football, he was a go.
Being forced to stand on the sidelines for the past three weeks took its toll on the senior quarterback, who returned to Stanford's starting lineup and led the Cardinal to a 41-31 victory over visiting Arizona on Saturday.
"It doesn't feel good. It's awful," Costello said of being sidelined. "Not playing a few weeks I have to challenge myself in terms of energy."
An energized Costello threw for 312 yards and three touchdowns after missing three games with a thumb injury. He was 30 of 43 passing with no interceptions. Back-up Davis Mills, out with a calf injury, was unavailable.
"I feel a whole lot different playing than not playing. It's everything," Costello said. "When our offense plays the way we know we can, when we're able to run the ball, you can see the full complexion of the offense and what we want to do."
Showing no signs of discomfort, Costello rifled passes to 12 different receivers, including a pair of touchdown passes to Simi Fehoko and one to Brycen Tremayne, whose only two career receptions have both gone for touchdowns.
"I haven't hit an inside pass to Simi all year," Costello said. "It felt good. I think the game has finally slowed down for him."
"A lot of this season I've felt rushed," he said. "Today it slowed down. It's good to have him back, leading the ship."
The Wildcats (4-4, 2/3 Pac-12) went with two quarterbacks, starting the athletic Kahlil Tate, who passed for 205 yards and a pair of touchdowns and rushed for 103 yards and a touchdown.
"Any time we can put points on the board I'm excited for us," Tate said. "I just want to move the ball up field."
"He brings energy that cannot be matched," Scarlett said of Costello. "Having him back, that shows you how dangerous our offense is and how dangerous he is."
J.J. Taylor rushed for 107 yards for the Wildcats, surpassing 3,000 for his career.
Freshman Grant Gunnell played two consecutive series in the first half, leading the Wildcats on an efficient eight-play, 65-yard scoring drive in which he completed all three passes attempted for 34 yards including an 8-yard scoring toss to Jalen Johnson.
"If he's not redshirting he needs to play, and he needs to learn in situations like today," Arizona coach Kevin Sumlin said. "You're not in mop-up time. We want to make sure that his growth continues."
Tate returned to the lineup after Stanford took a 21-10 lead and needed two plays to go 75 yards. Tate raced 57 yards for the score. He tucked the ball in after faking a pass and ran untouched.
CROSSING THE LINE
Stanford's offensive line has been banged up most the year and this was the second time all season the same players started back-to-back games. "Drew (Dalman) has been playing good football all year," coach David Shaw said. "He's been our mainstay in there. The young guys, bless them, they just go hard." Their play may have fooled Arizona's defense. "We underestimated their O-line," Wildcats' safety Tristan Cooper said. "They are better on the field than they were on film."
Arizona coach Kevin Sumlin doesn't call it a controversy. He's just trying to get the most out of his quarterbacks. It's a nice problem to have. Freshman Grant Gunnell, an accurate passer, entered the game for a series or two in each half, sparking a touchdown drive on his first series. The rest also seemed to ignite Kahlil Tate when he re-entered. Two unique quarterback styles will make it tough on opposing coaches who must prepare for both. "Everybody knew the plan before the game," coach Kevin Sumlin said. "I thought they both played well. We have to cut down our turnovers and penalties and press forward."
Nothing like getting your starting signal caller back in the lineup. K.J. Costello gave the Cardinal offense a huge boost. After scoring 16 points in its last game with the No. 3 QB, Stanford scored 31 in the first half against the Wildcats. Costello gives his team a hit of confidence that could lead to another winning season.
Arizona hosts Oregon State on Saturday.
Stanford has a bye next week and travels to Colorado on November 9.
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