LLANO, Texas — There seemed to be no stopping Dak Prescott and the Dallas Cowboys. They won 11 straight games with the rookie quarterback. They had the best record in the NFL. Prescott, a fourth-round draft pick, was being seriously discussed as the league’s Most Valuable Player.

Then came a 3-point loss to the New York Giants, and now everything is upside-down. Prescott is in danger of losing his job after his impersonation of Brock Osweiler that followed a shaky performance (134 yards passing) in a narrow victory over Minnesota.

Waiting to supplant Prescott – or at least share time — is the veteran Tony Romo, whose fractured back led to his ascendance.   So now we have the mother of quarterback controversies: debate over what to do with Romo.

There’s no consideration of starting him against the Tampa Bay Buccaneers on Sunday night against a team whose defense may be as formidable as the Giants’.   But there’s lots of discussion of using Romo as a relief pitcher if Prescott falters again.

It’s not true that a team can’t win by alternating quarterbacks. The Miami Dolphins played in the 1982 Super Bowl with Don Strock, a superior passer, splitting time with the more mobile David Woodley to create the moniker Woodstrock.

When owner Jerry Jones was asked what scenario might develop that would prompt a return by Romo, he appropriated a quote by a Supreme Court justice regarding pornography: “You’ll know it when you see it.”

So that left the door ajar if not wide-open.

One scenario, which Jones should have mentioned but did not, is the matter of giving Romo some game-time experience.  He had only the briefest of preseasoning before his surgical interlude.   Just three games remain in the regular season, and there’s always a chance of injury to a quarterback who runs as often as Prescott does. Romo needs to be ready.

Trent Green said on NFL Monday QB: “If the playoffs come and he hasn’t had any reps, that would be a mistake.” 

If Jones had been at the top of his game, he could have proposed that “sure, Tony will get a few game-time reps, but we’re not going to say when. Have to keep the defenses guessing.”

Perhaps then you could spring Romo, and if he did an extraordinary job, who could blame the team for trying that experiment again?

The point here is to reach the Super Bowl, which, granted, Romo has never come close to doing in his 14 years in Dallas. The truth is that Romo, with his Pro Bowl resume, his experience, his pocket presence, his uncanny timing with ace receiver Dez Bryant, is a much more promising bet for postseason success than any rookie, even one as supremely talented as Prescott.

Prescott put up splashy numbers over the first half of the season partly because he was exempted from facing a pass rush.   Another precocious Cowboys rookie, Ezekiel Elliott, pounded the defenses on the ground, so Prescott threw over a stacked box to a fleet of talented receivers who faced, at most, one on one coverage.

It was a picnic for him, shielded as he was by the league’s finest offensive line and attacking a row of mostly leaky defenses. The exceptions were the Giants, who have beaten Dallas twice, the Eagles, who lost in overtime, the Ravens, who lost by 7 to the Cowboys, and the Vikings, who lost to them by 2.

We’ve seen that good defensive teams are able to limit Elliott’s explosiveness and fire up the heat on Dak, causing the Dallas offense to stall.

In Sunday’s loss at MetLife, Prescott was slow reacting to combined pressure from the left and right. He was sacked three times, and he threw two interceptions, though one could be blamed on Bryant, who stumbled and fell to the ground as the ball approached.

Throughout the Cowboys’ win streak, Prescott faced few third-and-longs. As he observed after Sunday’s game, “We haven’t been in third-and-short as many times as we were earlier in the year.”

Against the Giants, he converted only one of 15 third downs after succeeding on just one of nine against Minnesota.   The Vikings, like the Giants, have a very quick defensive front and exploited the one weak link in the Dallas line, slow-footed right tackle Doug Free.

Third-down conversion is typically a problem for rookie quarterbacks as they try to catch up to the speed of the NFL. Philly’s Carson Wentz, who like Prescott has faded a bit after a torrid start, recently had a stretch of 0-for-24 on third and 8+ yards.

The Cowboys are kidding themselves if they think Prescott will not have difficulty in the playoffs when he faces more of these talented, quick defenses coached by smart tacticians. As the season goes on, more video is accumulated on the rookies, and defensive players and coaches become aware of their vulnerabilities.

To ignore Tony Romo at a time like this is absurd. He is popular with his teammates, and it’s not going to unsettle the locker room to put him into a game. Jones is paying him $18 million this season. Surely he wants him to do more for his money than hold a clipboard.