HOUSTON – Seeking clarity, the Raiders are trading the dry desert heat of Las Vegas for the thick August humidity of southeast Texas this week.

Waiting for them in Houston is something far more valuable than comfortable weather: answers.

Specifically, about an offensive line the Raiders believe is headed in the right direction but still needs to prove it. About its ability to protect whoever ultimately lines up at quarterback. And about whether it can consistently create running room for Ashton Jeanty and an offense Klint Kubiak intends to build from the ground up.

They could not have handpicked a better measuring stick.

The Texans boast one of the NFL’s best, deepest and most physical defenses, particularly up front, where they can stress an offensive line in ways the Raiders simply can’t manufacture against themselves every day.

That makes Tuesday’s joint practice less about winning individual reps and more about discovering exactly where the Raiders stand.

A year ago, their offensive line ranked among the NFL’s biggest liabilities. Today, there are legitimate reasons to believe a revival is underway. Pro Bowl center Tyler Linderbaum has been dropped into the middle of the operation. Kolton Miller is back at left tackle. And Kubiak and veteran offensive line coach Rick Dennison have brought a scheme and teaching philosophy designed to create cohesion, movement and a more dependable running game.

There have been encouraging signs throughout training camp.

Houston represents the reality check.

If the Raiders’ offensive line really has taken the step forward they believe it has, there may be no better place to prove it than against a Texans defense capable of exposing every weakness, communication breakdown and technical flaw.

And if there are still cracks in the foundation?

Better to find them now than in September.

It goes deeper than that, of course.

After investing the first overall pick in the NFL draft on Indiana Heisman Trophy winner and national champion Fernando Mendoza, the Raiders appeared determined to resist the temptation that has sabotaged so many young quarterbacks over the years: asking him to do too much, too soon.

The plan was patience.

By signing veteran Kirk Cousins, the Raiders gave themselves the luxury of bringing Mendoza along at a deliberate pace, with Cousins holding down the job until the rookie proved he was ready to take it from him.

The operative word, though, is proved.

And Mendoza may already be putting some pressure on that timeline.

His preseason debut was encouraging on the surface — 10 completions on 16 attempts for 97 yards and a touchdown — but the numbers were almost secondary to how he produced them.

Mendoza looked comfortable, poised and in command. He worked through progressions rather than locking onto his first read, repeatedly getting to his third and, at times, fourth option. He processed what the defense showed him, stayed composed when the initial answer disappeared and delivered the ball with conviction.

Those are meaningful traits for any quarterback. For a rookie taking his first NFL snaps, they are particularly encouraging.

One preseason game shouldn’t blow up a carefully constructed development plan.

But when a young quarterback starts showing you he might be ahead of schedule, you’d better be willing to adjust the schedule.

“I saw the same guy that we’ve seen in practice,” Kubiak said. “I see an ascending player.”

Which makes Tuesday’s joint practice an intriguing next step.

Not just for an offensive line looking to prove its improvement, but for a rookie quarterback beginning to raise an entirely different question than the Raiders expected to be asking this soon:

How long will they actually need to wait?

The Raiders have a rare luxury in Cousins. He can buy them meaningful time and prevent them from forcing Mendoza onto the field before he is ready.

The challenge, of course, is determining exactly what “ready” looks like.

NFL teams have wrestled with that question for decades. There is no universal formula, no magic number of practices or preseason snaps that tells a team when a young quarterback has crossed that threshold.

Which is why reps against a defense like Houston’s are so valuable.

The Texans can speed up Mendoza’s clock, muddy his reads, pressure his protection and force him to solve problems he hasn’t necessarily encountered against the same teammates every day in training camp.

How he responds won’t settle the quarterback question.

But it could provide another important piece of evidence.

“There’s not one thing we’re looking for. There’s a million things,” Kubiak said. “But we’ve got to get him focusing on the details of each play and take it one rep at a time, down to down. And if he has that mentality, as well as the other guys, they will continue to improve.”

That, ultimately, is why the Raiders sought out the Texans.

They wanted a late-summer stress test, for their offensive line, their running game, their protection and, increasingly, their young quarterback.

Tuesday, they find out what bends, what breaks and, perhaps most importantly, what might be further along than they thought.