HENDERSON, Nev. (AP) — The Raiders' offensive line is far from proven, no wide receiver has emerged as a true No. 1 and a rookie could be the starting running back entering the season.

Probably not the ideal situation to start a first-year quarterback, but players drafted first overall — as Fernando Mendoza was — usually join a team with a lot more questions than answers.

And there are plenty with Las Vegas.

Could that be a factor for when Raiders coaches decide to start Mendoza? He likely will be the backup to Kirk Cousins when the season opens Sept. 13 against Miami.

“They’ve all got to get ready,” coach Klint Kubiak said. "Whoever is playing quarterback for us, it’s a team thing. It’s not the QB playing well and everyone else is not or the other way around.”

The Raiders' offense last season was statistically the worst in the NFL. Las Vegas' averages of 14.2 points and 245.2 yards per game were each last in the league.

It didn't help that the Raiders' offensive line also was statistically at the bottom, but management hopes that is no longer the case. The club signed three-time Pro Bowl center Tyler Linderbaum to the richest contract ever for an interior offensive lineman. Kolton Miller, who missed all but four games last season because of an ankle injury, is one of the league's best left tackles.

But how much the Raiders improve up front remains a question, particularly at right guard where Jackson Powers-Johnson is competing with Caleb Rogers for the starting role.

Also questionable is how the receiving corps will perform even without a clear-cut first option. Kubiak criticized the receivers after Thursday's 22-20 preseason victory at Houston.

“When you go out and you have trouble with your assignments, I’m going to have an opinion about it, and it’s not just them,” Kubiak said Tuesday. "We’ve had plenty of other guys that have got to step up. A lot of young guys, and then guys that we’re counting on in that receiver room.”

Now there's also the significant question at running back after second-year starter Ashton Jeanty went down with an injury in practice Sunday. He was unable to put pressure on his right leg as he was helped off the field, and the Raiders have been quiet about his prognosis.

Rookie Mike Washington Jr., drafted in the fourth round, is taking first-team snaps in practice. He also has performed well enough in training camp that he was getting some of those repetitions even when Jeanty was healthy.

So the Raiders have some decisions to make, most notably at quarterback and when to turn the offense over to Mendoza, the Heisman Trophy winner last year at Indiana. It seems like a matter of time before Mendoza takes over, and Kubiak continues to insist it's an ongoing competition even with Cousins still quarterbacking the starting offense in practice.

But as Kubiak said, the decision on when to play Mendoza will depend on the quarterback and not the offense around him.

“We’re trying to grow in all phases of our offense, every player, every position group,” offensive coordinator Andrew Janocko said. "Ultimately, coach (Kubiak) has the final say on how and when we’re going to play this person, that person, and not just quarterback, but any position group, and how players develop over time. We like to see the guys develop in practice, we like to see what they’re doing in these preseason games and then basing decisions on that.”

Mum's the word on Jeanty

Kubiak was asked several ways Tuesday about Jeanty's health, and he refused to bite.

Raiders players and coach knelt and prayed when Jeanty was hurt.

“I think that says a lot about him being on the mend and us counting on him,” Kubiak said, the closest he came to providing an indication on where Jeanty stands. "So really excited to get him back, and I’m a huge believer in the power of prayer.”

Smooth transition behind center

One of the major questions regarding Mendoza was how he would be able to adjust to taking snaps directly under center. He took snaps out of shotgun almost exclusively at Indiana.

Linderbaum didn't even realize that was the case, an indication of how well Mendoza has adjusted.

“Under center, he’s perfect," said Jordan Meredith, the backup center who has worked most closely with Mendoza. "I’ve had no issues the whole time. He’s been detail oriented in the huddle, taking command of every play that he gets. I see that he’s ready for anything the coaches ask of him.”

Brother vs. brother

The Raiders host San Francisco on Thursday night in the final preseason game for both teams. Kubiak's brother, Klay, is the 49ers' offensive coordinator.

“My brother is the smartest guy in the family, and I’m not kidding," Klint Kubiak said. "He’s brilliant, works really hard. I love him. Not going to love him on Thursday night.”

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