Former UCLA quarterback Josh Rosen aims to take out Cardinals’ frustrations on Chargers

Josh Rosen is only eight games into his NFL career, but he already clearly understands the business side of the game.

In a conference call with reporters Wednesday, the former UCLA standout was asked about the toughest part of this 2-8 season with the Arizona Cardinals. In answering, he referenced his two Cardinals predecessors in a rather hard-facts manner.

“Just trying to stay positive through the whole thing,” Rosen said. “I mean, it’s frustrating … But $20 million of your salary cap is going to a quarterback that’s not playing and you got your OC [offensive coordinator] fired. It’s just trying to stay positive and keep all the guys going in the right direction.”

Sam Bradford and Carson Palmer, neither of whom is still with the Cardinals, represent a cap hit of slightly more than $17.5 million this season.

Bradford started the first three games before being benched in favor of Rosen. He was released this month.

Palmer, Arizona’s previous starter, had his 2017 season end when he suffered a broken arm in Week 7 against the Rams. He retired in January after 15 NFL seasons.

Arizona changed offensive coordinators in October, replacing former Chargers coach Mike McCoy with Byron Leftwich.

“It’s not that it’s been hard,” Rosen said. “It’s just been kind of frustrating at times. … You kind of have two options. You can quit or keep pushing on and I don’t quit. So I will continue to push on.”

The Cardinals drafted Rosen with the No. 10 pick last April. He signed a four-year, $17.5-million contract two weeks later.

In his first eight games, seven of them starts, he has completed 125 of 228 passes for 1,416 yards and nine touchdowns with 10 interceptions.

Among quarterbacks with at least 25 pass attempts, his completion percentage (54.8) ranks 42nd.

“Very talented,” Chargers coach Anthony Lynn said of Rosen. “[Can] make a lot of throws. Liked him coming out of school. … He’s going through some growing pains, but he’s going to be a really good quarterback in this league.”

Rosen has at least one ally in Lynn’s locker room. Rookie offensive lineman Scott Quessenberry was Rosen’s center during their time at UCLA.

Quessenberry said the two remain friends and talk regularly, though they haven’t spoken this week.

“I’ll shoot him a text message,” Quessenberry said. “Love Josh. He’s a great dude.”

After three years as Rosen’s college teammate, Quessenberry said he has no doubt about his buddy’s pro potential.

“I think he could be one of the all-time greats,” Quessenberry said. “He can make all the throws. He’s going to have the support of his teammates. He’s a guy everybody gets along with. I think he’ll have a good, long career.”

The game Sunday at StubHub Center will be a first for Arizona.

Rosen, however, won a state championship in the stadium in 2013, leading Bellflower St. John Bosco past Concord De La Salle.

“I remember hopping up into the stands, hanging out with my buddies, raising the trophy,” Rosen said. “Very fond memories.”

Liuget on IR

The Chargers placed Corey Liuget (knee) on injured reserve and claimed T.Y. McGill off waivers from the Philadelphia Eagles in a swap of defensive linemen.

McGill was with the Chargers for the first four games but did not play. He appeared in two games for the Eagles this month and was credited with three tackles.

Liuget suffered a season-ending injury in Sunday’s 23-22 loss to the Denver Broncos.

The Chargers announced that he underwent successful surgery to repair a damaged quadriceps tendon Wednesday. Recovery time for such a procedure is six to nine months.

Benjamin returns

After defensive back Desmond King assumed punt return duties for a few games, the Chargers have gone back to Travis Benjamin the past two weeks. Benjamin sat out four games because of a foot injury.

Lynn explained that he likes Benjamin’s speed in that spot. He was the Chargers’ primary punt returner in 2017.

Lynn said he also was wary of overusing King.

“Desmond is playing a lot of football for us,” Lynn said. “At one point, he’s playing 65% of the snaps on defense. He’s the kick returner. He’s the punt returner. We try to give him a little bit of a break too.”

Etc.

Wide receiver Tyrell Williams (quadriceps) did not practice. The Chargers didn’t disclose the severity of his injury. Running back Austin Ekeler (neck) was limited during the workout. He was hurt Sunday. … Lynn said that defensive end Joey Bosa will return to the starting lineup against Arizona. Bosa sat out the first nine games because of a foot injury before making his season debut Sunday.

jeff.miller@latimes.com

Twitter: @JeffMillerLAT