OXNARD, Calif. -- Rookie Dak Prescott has already passed the eye test with the Cowboys. He looks the part of an NFL quarterback.

That's become evident the last two weeks as Prescott has shined in practice and was nearly perfect in his debut Saturday at the Los Angeles Rams.

But if Prescott is to begin the season as the Cowboys' backup he must also survive the history test.

Cowboys coach Jason Garrett prefers a veteran as his backup quarterback. Since Tony Romo became the Cowboys' starter in 2006, he's always had a veteran behind him.

History tells you the Cowboys won't sit tight and keep Prescott as the backup. The average age of the Cowboys' primary backup quarterback since Romo became starter is 34.7 years old. Prescott just turned 23 two weeks ago.

The youngest primary backup quarterback the Cowboys have had to start a season behind Romo was Kyle Orton in 2012 at 29.

So the Cowboys have not only used a veteran backup behind Romo but also it's usually been one at the end of his career.

Drew Bledsoe retired after 2006. Brad Johnson retired after 2008. Jon Kitna retired after 2011. Orton told the Cowboys he was retiring after 2013, though he came back to play one more season with the Bills.

See a pattern?

Prescott doesn't fit the trend. Perhaps that's a plus considering the Cowboys' backup philosophy has been a flop since Garrett took over as offensive coordinator in 2007.

The Cowboys are 7-20 when starting a backup in place of Romo. That includes a woeful 1-11 mark last season using Brandon Weeden, Matt Cassel and Kellen Moore. The Cowboys are 1-13 when starting a backup the last three seasons.

Prescott not only represents a fresh face but also a fresh perspective.

Maybe it's time for the Cowboys to move away from a veteran backup.

The Cowboys drafted Prescott in the fourth round with every intention of giving him a redshirt year in 2016 as he made the transition to playing under center for the first time.

But the Cowboys' plan took a wrong turn four days into training camp when backup Kellen Moore fractured his right ankle. He's out the next three to four months.

Suddenly, Prescott isn't viewed as a luxury. He's become a necessity.

"Initially, Kellen was here and Dak was kind of in the transition phase from college to the pro game and he was picking it up fast," Cowboys quarterbacks coach Wade Wilson said Monday, "but once Kellen went down, it got expedited pretty quickly."

Cowboys coaches and scouts were told over and over again about Prescott's leadership, poise and work ethic during their research before the draft. They've now seen that come into fruition, culminating in a near-flawless first half in the preseason opener Saturday against the Rams.

Prescott led Dallas to a 24-7 halftime lead. He was 10-of-12 passing for 139 yards and two touchdowns. By NFL terms, a perfect passer rating is 158.3. Prescott finished Saturday with a 154.5 rating.

Wilson said Prescott could have easily been 12-of-12 passing Saturday. Both his incompletions were dropped passes by tight end Geoff Swaim.

Prescott hasn't just turned the heads of the Cowboys front office and coaches, however. Cowboys' veterans are already buying into the rookie.

Wilson said he talked to all four veteran offensive line starters after the preseason game against the Rams to gauge how Prescott was in the huddle.

"They said he was great in the game, a lot of poise in the huddle," Wilson said. "It's been a real steady learning curve."

Wilson said the Cowboys plan to be patient with Prescott and third-stringer Jameill Showers. They won't make too much of Prescott's preseason debut.

"This year with the players that we have behind Tony and giving them a chance, compared to what's out there right now and trades and salary cap, all those things factor in, but I think the overriding factor is we like the young guys who are here. They've shown a lot of promise.

"With guys who haven't played there's always a wildcard. So far, Dak and even Jameill have shown the capacity they can go out there and function and hopefully that continues throughout the preseason and I'm sure there will be a decision to be made down the road."

Twitter: @DMN_George

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