Colorado’s Lucas Siewert rebounds in front of Washington State’s Jervae Robinson during the January 23, 2020 game in Boulder.(Cliff Grassmick/Staff Photographer)

During shoot-around on Thursday, Colorado head coach Tad Boyle watched senior Lucas Siewert and had a bit of regret.

“I was just so mad at myself for not redshirting him as a freshman,” Boyle said after the Buffaloes’ 78-56 win against Washington State at CU Events Center on Thursday night. “He’s become such an integral part of this program and his teammates really trust him.”

Siewert has come a long way from averaging 2.7 points and 11.5 minutes as a freshman, and against the Cougars he stepped into the starting lineup for the first time this season, filling in for injured Tyler Bey, and didn’t blink.

“A little bit (of an adjustment), but I knew it was going to happen the day before because Tyler didn’t practice,” Siewert said after scoring a game-high 16 points and pulling down 10 rebounds. “Coach told me just to go out there and play my game. I’ve started before, so it was nothing new, but it was a little bit of an adjustment.”

Siewert started 26 games a year ago, but has been coming off the bench this season. His 7.8 points and 4.4 rebounds per game have been important to the 23rd-ranked Buffs (15-4, 4-2 Pac-12), but Thursday was one of his best games of the season. He had his second-best point total of the year and recorded the third double-double of his career.

“Lucas Siewert is a starter; he just doesn’t start for Colorado, but he’s playing starter minutes and he’s got the confidence of a senior,” Boyle said. “(He) steps in like it’s no big deal and has 16 and 10 and plays more minutes than he normally does and handles the challenge.”

The challenge was to try to make up for the loss of Bey, who leads the Pac-12 with 9.33 rebounds per game and ranks 16th in scoring at 13.1 per game.

“We knew Tyler averages nine-plus rebounds a game, so we weren’t going to have those tonight,” Siewert said, “so coaches told me, and even Tyler told me, to come out aggressive.”

Colorado’s Dallas Walton shoots over Washington State’s Jeff Pollard during the January 23, 2020 game in Boulder.(Cliff Grassmick/Staff Photographer)

Offensively, Siewert drained a 3-pointer early and hit two more later in the game. He also went 5-for-6 at the free throw line.

He wasn’t alone in filling Bey’s shoes. Junior Dallas Walton gave the Buffs a solid 12 minutes, with season highs of seven points and four rebounds.

It was just the third time this season Walton has played more than nine minutes in a game. He might have played more, but WSU forward Jeff Pollard left the game for several minutes after injuring his hip.

“It was great to have Dallas out on the floor,” Boyle said. “I was glad to see Pollard come back in the game because he was their big bruiser that we felt like Dallas really could match up with well. (Because Pollard went out), we weren’t able to get him as many minutes in the second half as I would have liked to, but Dallas keeps getting better, keeps improving in practice.

“I said we’re going to need him at times this year; tonight was one of those times.”