ARLINGTON, Tex. — Saquon Barkley spent most of the first three quarters Sunday on the Giants’ sideline. He was not hurt or benched. To the contrary: On their second play from scrimmage, he surged through a hole, shook a Dallas defender and sprinted down the sideline for a 59-yard gain.

Barkley loitered away from the action because, as a running back, he does not play defense. Though perhaps he should have Sunday, when the Giants’ inability to cover, tackle or generate any semblance of a pass rush hastened a 35-17 loss at AT&T Stadium that exposed the chasm of roster talent separating them from the reigning N.F.C. East champion Cowboys.

The Giants closed the first half by allowing touchdowns — all on Dak Prescott passes — on three consecutive drives. The Giants opened the second half by allowing touchdowns — another Prescott pass, an Ezekiel Elliott run — on consecutive drives.

“It was a different guy every time,” safety Michael Thomas said.

He was referring to his teammates, whose communication and technique breakdowns produced five Dallas scoring drives of at least 75 yards (including three of 83 or more). But he also could have been lamenting the Cowboys’ balanced offense, with Prescott throwing for 405 yards — and from a clean pocket — and five different players scoring touchdowns. Outside their locker room afterward, the team owner Jerry Jones marveled at his squad’s balance, saying he hadn’t seen such unpredictability since Troy Aikman, Emmitt Smith and Michael Irvin were leading Dallas to three Super Bowls in the 1990s.