UCLA can’t hold onto 10-point halftime lead in 35-17 Cactus Bowl loss to Kansas State

Reporting from Phoenix —  For a half, it didn’t seem to matter who was coming or going for UCLA.

The combination of a fill-in quarterback and an interim coach worked just fine as the Bruins built a 10-point lead over Kansas State at the midpoint of the Cactus Bowl.

Quarterback Josh Rosen can’t play because doctors won’t clear him after a string of concussions? No worries. Devon Modster looked like someone new UCLA coach Chip Kelly might want running his offense next season should Rosen depart for the NFL as expected.

Jedd Fisch has to guide a team missing its primary star in what was possibly the interim coach’s last game with the Bruins? He’s got this. It seemed Fisch could keep trotting out the joke he used earlier this week when he noted that (at 1-0) he had a better winning percentage than veteran Kansas State counterpart Bill Snyder.

Things deteriorated considerably for UCLA in the second half of a 35-17 loss on Tuesday night at Chase Field, the Bruins’ defense reverting to its supple form from earlier this season and their once-humming offense badly sputtering.

There was also a return to the Bruins’ undisciplined ways, an unsportsmanlike conduct penalty on receiver Jordan Lasley while standing on the sideline and a facemask on safety Jaleel Wadood contributing to the Wildcats’ final touchdown drive.

The ending was about as ugly as imaginable for UCLA (6-7). Kansas State (8-5) outscored UCLA 28-0 in the second half, punishing the Bruins with a relentless ground attack while limiting them to four first downs.

“Some self-inflicting wounds,” Fisch said. “I think at the end they kind of wore us down a little bit. They just held the ball and held the ball and we didn’t have a chance, and we needed to convert. But I couldn’t be more proud of our team.”

Remember the 2015 Alamo Bowl, when the Bruins nearly squandered a 31-6 halftime lead against Kansas State before holding on?

This was much worse for the Bruins. Their 17-7 halftime advantage Tuesday didn’t stand a chance given the onslaught of misfortune.

Kansas State totaled 344 rushing yards, including a 41-yard touchdown run by Alex Barnes on fourth and one early in the fourth quarter that seemed to drain any remaining will to compete from the Bruins.

“It’s kind of really frustrating, kind of going throughout the season, trying to stop that talk that’s going around for the UCLA defense,” said Bruins defensive end Jacob Tuioti-Mariner, who logged both of his sacks in the first half. “Seeing that happen for the last game, it was frustrating, it was disappointing, but I know I could have done better out there. Starting from me.”

Kansas State’s comeback had started on another fourth down midway through the third quarter, quarterback Alex Delton surging ahead from the one-yard line amid a scrum of players into the end zone. The touchdown pulled the Wildcats to within 17-14.

UCLA tailback Bolu Olorunfunmi fumbled on the next offensive play, giving the ball back to Kansas State on the Bruins’ 24-yard line. Wadood compounded the situation when he missed a tackle after Wildcats receiver Dominique Heath had taken a short pass from Delton, allowing Heath to run into the end zone for an eight-yard touchdown that gave Kansas State a 21-17 lead.

Modster made only his second career start after Rosen came out in uniform for warmups before being held out by doctors who wanted to safeguard his health after he suffered two concussions in a span of less than a month.

“He practiced the whole week and he looked good,” said UCLA receiver Theo Howard, who hauled in a 70-yard touchdown pass in the second quarter that gave the Bruins a 17-7 lead. “Nothing different. … I know he would like to be out there with his team just because he’s done a lot for us and he’s the type of player who will fight to get on the field.”

Modster completed 21 of 34 passes for 295 yards and two touchdowns but was far less effective after leading UCLA to that 10-point edge at halftime. The Bruins also ran for only 69 yards and averaged 2.8 yards per carry.

“I just threw too many incomplete passes,” said Modster, who completed 11 of 20 for 80 yards in the second half. “That’s pretty much it.”

Howard suggested that UCLA lost momentum after receiver Eldridge Massington dropped a pass in Kansas State territory on third down on the team’s first drive of the third quarter.

Modster got UCLA’s offense rolling early in the second quarter when he completed a short pass to Lasley that went for a 52-yard touchdown after Lasley cut outside and picked up a block from fellow receiver Christian Pabico. Lasley celebrated by waving to Bruins fans sitting behind the end zone.

Lasley had 128 yards, his seventh game of 100 or more yards this season, but most of the highlights the rest of the game belonged to the Wildcats.

“It’s very disappointing especially when you’re heading into the half feeling very confident and the score ends up not being in your favor,” Tuioti-Mariner said. “It’s extremely disappointing.”

ben.bolch@latimes.com

Follow Ben Bolch on Twitter @latbbolch