Oregon rolled through its nonconference schedule, winning its first 12 games by an average of 16.0 points.
Pac-12 play hasn't been as kind to the No. 17 Ducks, who will look to snap a two-game losing streak Sunday when they host Stanford.
The Ducks (13-2, 1-2) won their conference opener at Utah but have since lost to Colorado and California. They shot a season-worst 26.3 percent (5 of 19) from 3-point range in a 96-83 loss to the Golden Bears on Thursday.
Through three Pac-12 games, the Ducks are shooting just 40.7 percent from the field, far worse than their 51.3 percentage against nonconference opponents.
"We've got to do some soul-searching, we've got a lot of work to do," coach Dana Altman said. "We've just been really exposed the last two games."
The issues aren't relegated to Oregon's offense. The team's defense has also taken a step back during the two-game skid and was especially poor versus Cal. Oregon allowed Colorado and Cal to shoot a combined 54.3 percent with an average of 98.0 points allowed.
The Golden Bears assisted on 21 of their 32 field goals, made 26 of 29 free throws and scored 50 second-half points against the Ducks.
"Letting guys score so much points on us, it's going to be tough to win games that way," said forward Mike Moser, who had 15 points and 10 rebounds against Cal.
"Numbers don't lie ... there are some thing we can prevent. A lot of easy buckets inside, guys were out of position, we fouled more than we wanted to. Those things all lead to points as well."
The Cardinal (9-5, 0-2) have also struggled in conference play, dropping back-to-back games to Cal and Oregon State.
A lack of outside shooting has been a major problem for Stanford, which has made only 6 of its 22 3-point attempts in league play - a percentage of 27.3 that is among the Pac-12's worst. That number goes against the team's trend in nonconference games. Stanford is hitting on 40.6 percent from 3-point range overall this season - which leads the league.
Among the bright spots for the Cardinal has been junior shooting guard Chasson Randle, who leads the team with 19.2 points per game. He is coming off one of his best performances of the season, scoring 30 points in Thursday's 81-72 loss to the Beavers. Randle went 10 of 18 from the field and hit all nine of his free throws.
Stanford got within two several times late in the second half but couldn't move ahead.
"I thought we played the full 40 minutes trying to make plays," coach Johnny Dawkins said. "We got back in the game and cut it to one or two possessions and we just couldn't get over the hump."
Randle played well in Stanford's only other matchup with a ranked team so far this season, finishing with 22 points and five rebounds in a 53-51 upset of then-No. 10 Connecticut on Dec. 18.
Oregon has won three of its last four against Stanford, though the Ducks trail the all-time series 90-48.