During their 11-game winning streak that established the Cowboys as a Super Bowl favorite for many, rookies Dak Prescott and Ezekiel Elliott and the entire offense had their way with everyone in NFL.
An opening-game loss to the New York Giants separated them from perfection. A second loss to Ben McAdoo and his boys in December has brought Jerry Jones' team back to reality.
The Giants (9-4) have the Cowboys' number, especially on defense.
New York has limited Dallas (11-2) to 26 points in beating it twice, and the Giants have made the Cowboys' offense look beatable.
Take a look at Sunday night's 10-7 win. New York held Dallas to a season-low 260 total yards, limited it to 1 of 15 on third-down attempts, and forced three turnovers, the last coming late in the fourth quarter on Dez Bryant's only reception of the game.
"We were not able to produce offensively, but it was good to see the guys on the defense battle like that," said Elliott, who rushed for 107 yards on 24 carries. Prescott was 17 of 37 for 165 yards, a touchdown and two interceptions.
"It was poor execution; we were not at our best and we kind of beat ourselves. In the NFL, you are playing great athletes and you will not have success every week, and today we did not have success."
The Cowboys have three games left to get their offense back in gear, but the Giants have laid the groundwork for them. It's the same formula the Giants used in winning two Super Bowls under Tom Coughlin. Their defense is getting a pass rush and they have the defensive backs to shut down receivers.
Bryant had two catches in two games against the Giants.
Elliott didn't break anything longer than 15 yards Sunday night.
Dallas' long touchdown came on a 31-yard pass from Prescott to Terrance Williams on a busted play by the Giants' defense.
"Honestly, we beat ourselves. When we don't beat ourselves we are a different football team," said Elliott, who was limited to 51 yards rushing in the season opener. "We need to go out there, eliminate mistakes, execute, and we will be good."
Dallas coach Jason Garrett said the Cowboys really struggled on third down, especially passing the ball.
"We've been one of the better third-down teams in the National Football League," he said.
Bryant was at a loss for words to explain the performance. It was everyone who struggled, he said, adding don't blame the rookie quarterback for Dallas failing to clinch the NFC East and lock up a first-round bye in the playoffs.
"It's not his, it's ours," Bryant said of the fault. "It wasn't our best night. We all made mistakes, and we're going to go back in and fix them. Don't try to single him out."
For the Giants, it was a remarkable performance in their first game without star defensive end Jason Pierre-Paul, who will be sidelined the rest of the regular season after having surgery for a sports hernia.
"Guys stepped up," linebacker Jonathan Casillas said. "That's what we said before. JPP, one of the better players in the NFL, you can't replace him with one person, so the whole group stepped up. I feel like we played lights out on defense."
The Cowboys felt the Giants played that way, too, particularly on those third downs.
"It's something we've got to get cleaned up," Prescott said. "The last two weeks, we haven't been as good as we were the rest of the year. Whatever it is, protection, receivers getting open, me getting the receivers the ball, we'll get it checked out and get it fixed."