Eventually, the Cal men’s basketball team will need to diversify its offense.

But to defeat CSU Bakersfield in their season opener Sunday night, all the Bears needed was a heavy dosage of Justin Cobbs and Allen Crabbe.

The pair of junior guards outscored the Roadrunners in the first half, building an early lead that concluded with a 78-65 victory at Haas Pavilion.

“It’s always nice to win the first game, because you’re never sure you’re gonna win another,” said Cal coach Mike Montgomery. “The first half we were very efficient.”

Cobbs scored the game’s first basket on a mid-range fadeaway, as the Bears never trailed. The point guard excelled in transition, scoring on fastbreak layups and an array of floaters for a total of 22 points on 8-of-11 shooting.

The Roadrunners (0-2) could not find an answer for Crabbe either, especially in the first half. Against CSUB’s 2-3 zone, Cal would patiently pass the ball around to set up open 3-point attempts for Crabbe, and the swingman lit up the Roadrunners for 20 points in the opening period, sinking all four of his 3-pointers. He finished with a game-high 27 points in just 29 minutes of play.

“I guess I got going early,” Crabbe said, “and my teammates kept finding me.”

Added Cobbs, “I love playing with this man. We just feed off each other.”

Cal’s defensive effort was just as crucial as its star guards’ offensive exploits.

After he saw his squad give up 80 points to San Francisco State in last week’s exhibition win, Montgomery expected improvement on the defensive end.

What he got was a defense that held CSUB to under 35 percent shooting.

There was forward Richard Solomon taking consecutive charges midway through the first half, while Cobbs and Crabbe were jumping passing lanes throughout the game. Senior forward Stephon Carter led the Roadrunners with 15 points, but it took him 16 shots to do it.

After nearly every missed CSUB basket, the Bears pushed the ball for easy transition buckets. As Cobbs put it after the game, layups should be 100 percent, and that was reflected in Cal’s 53 percent shooting night.

“Once we get stops and get on the break, we’re hard to stop,” Cobbs said.

Back-to-back fastbreak layups by Cobbs and Crabbe put the Bears up 30-9 midway through the first half, but it wasn’t just the guards scoring in transition.

The Bears’ big men ran the floor too — and were rewarded for it. Early in the second half, Solomon grabbed a rebound, dribbled up the floor and found Crabbe, who tossed an alley-oop to Kravish to put the Bears up, 57-35.

However, that was Kravish’s only basket. The 6-foot-9 forward  had nine rebounds but took just two shots.

“He’s got to get more touches than that,” Montgomery said.

The coach was also disappointed with his squad’s rebounding effort. While Cal had the overall edge on the glass, CSUB pulled down 19 offensive boards in the contest.

“We’ve just somehow, some way got to shore that up,” Montgomery said. “We’ll continue to work on our block-offs. We got some big guys who just stand. David Kravish worked pretty hard to rebound, but he was pretty much by himself.”

The offense was mainly two guys, as Cobbs and Crabbe combined for just over half of Cal’s shot attempts.

Without a reliable third or fourth option yet, Montgomery knows that his team could be in trouble if the duo has an off night. Missouri transfer Ricky Kreklow could be that extra offensive punch. Montgomery said that the injured swingman could make a cameo appearance on Tuesday in the Bears’ 6:30 p.m. Haas Pavilion tilt against Pepperdine (0-1).

For now, though, Crabbe is not worried about shouldering the offensive load with Cobbs.

“It’s still early in the season,” Crabbe said. “We have guys who are capable of scoring. Things are just gonna take time.”