STANFORD – With or without Christian McCaffrey, Stanford’s offense struggled for the second straight week, falling to Washington State 42-16 on Saturday night at Stanford Stadium.

McCaffrey, the Heisman hopeful running back for the 15th-ranked Cardinal, was sidelined with an undisclosed injury in the third quarter. The junior was limited to just 35 yards on eight carries and one catch for five yards.

Stanford coach David Shaw would not speculate on how much time – if any – McCaffrey would miss.

“Don’t ask the question,” Shaw curtly told the media after the game. “I don’t have any answers for you.”

The loss was Shaw’s first against WSU, which had lost eight straight against Stanford (3-2, 2-2 Pac-12). It also marked just the second time in Shaw’s six-year tenure that the Cardinal had lost consecutive games.

After managing just one touchdown in its previous game, a devastating 44-6 loss at Washington on Sept. 30, Stanford once again had trouble finding the end zone. The Cardinal trailed Washington State 14-3 at halftime and failed to score an offensive touchdown until garbage time. It didn’t surpass 100 yards of total offense until the waning minutes of the first half.

“We were inefficient running the ball,” Shaw said. “We were inefficient on third downs. We were efficient at times throwing the ball, and at other times we were inefficient. Inefficiency is not the sign of a good football team.”

J.J. Arcega-Whiteside scored Stanford’s only offensive touchdown in the final seconds of the game, catching a 1-yard pass from quarterback Ryan Burns when the outcome was no longer in doubt.

Sophomore cornerback Frank Buncom returned an interception 26 yards for the Cardinal’s only other touchdown, cutting WSU’s lead to 21-10 with 7:44 remaining in the third quarter.

“We definitely needed a play, and I was happy to deliver for my teammates,” Buncom said. “Next time we’ve got to keep the momentum going.”

Although Burns threw for a career-high 233 yards – his first time cracking 200 – he continued to experience sack trouble. Brought down for losses six times at Washington, the senior was sacked four times against Washington State (3-2, 2-0) and lost a fumble on the second one.

“It’s a big burden on myself and the rest of the guys,” senior left guard David Bright said of the frequency with which Burns has been sacked. “We pride ourselves on keeping the QB clean every game. Ryan’s one of my best friends on the team – when he goes down, I take it personal.”

Even Conrad Ukropina, the Cardinal’s typically reliable placekicker, had a rough night. Although thesenior – who entered the game 6 for 6 on field goals – accounted for Stanford’s only first-half points, he missed two of three attempts in the first half, banging both off the uprights.

The Cardinal’s offense did pick up steam near the end of the first half. Burns completed 11-of-15 passes for 131 yards by the intermission, and senior wide receiver Michael Rector had five catches for 90 yards.

Stanford’s defense, meanwhile, didn’t fare much better. Cougars quarterback Luke Falk completed 30-of-41 passes for 357 yards and four touchdowns, including two to sophomore wide receiver Tavares Martin Jr.

Martin’s biggest TD came with 9:10 remaining in the second quarter. Facing fourth-and-7 at Stanford’s 29, Washington State decided to go for it instead of trying for a field goal – possibly because sophomore placekicker Erik Powell hadn’t put one through the uprights all season.

Falk hit Martin over the middle for a gain that would have gotten a first down. Martin then scrambled toward the left side, outraced several Stanford defenders and dove over the pylon for his second touchdown.

Stanford never got closer than 11 points after that.

n Sophomore safety Justin Reid was ejected following a targeting call in the third quarter. Reid had taken down Falk on the play.

Shaw said he couldn’t disagree with the call.

“There was contact to the head,” the coach said. “I understand it. It’s unfortunate because a player like (Reid) had to miss some playing time – he’s just coming into his own.”

— The Cardinal wore its all-black uniforms Saturday night. Stanford was 7-0 in those uniforms before Saturday’s loss.