ORCHARD PARK, N.Y. — Ron Rivera stood motionless at the 30-yard line, his arms crossed and his eyes fixated on the end zone as a sea of fans behind him erupted in cheers. For more than eight minutes of the third quarter, the Buffalo Bills picked apart the Washington Football Team on a demoralizing 17-play, 93-yard touchdown drive. Any chance of an upset fizzled, and any hope of a needed turnaround by Washington’s once-vaunted defense disappeared.

So Washington’s coach just stood there, saying nothing, as players jogged off the field and some, including star defensive end Chase Young, became visibly frustrated on the sideline.

In a game he billed as a “measuring stick” for his team, Rivera could only watch as the results defied his early-season expectations. With an imploding defense and a turnover-prone offense, Washington crumbled in its first road game of the season, losing to the Bills, 43-21, to fall to 1-2.

“My expectations were to play better than we did, to be honest,” he said flatly after the game. “... We got a long way to go.”

The Bills’ dominance was unrelenting, save for a three-minute stretch in the second quarter when Washington scored two touchdowns and briefly grabbed the momentum before losing it just as quickly. And while the mistakes came from all over, the burden was especially heavy for the defense, a group led by four first-round draft picks on the line.

Buffalo amassed 312 yards in the first half and finished with 481. More damning: It converted 60 percent (9 of 15) of its third downs, collected 29 first downs and scored five touchdowns.

Washington’s defensive line raised expectations with its play last season, when the edge-rushing duo of Chase Young and Montez Sweat, combined with the interior play of Jonathan Allen and Daron Payne, created trouble for opposing quarterbacks. This year, the group has failed to re-create that sort of pressure.

The Bills’ Josh Allen wasn’t sacked Sunday, and the minimal pass rush he faced gave him an average of 2.94 seconds to throw, per the NFL’s Next Gen Stats. Allen struggled with his accuracy in the first two weeks, but he had little issue against Washington, completing 32 of 43 passes for 358 yards and totaling five touchdowns (one rushing). Including his nine rushing yards, Allen outgained Washington by 77 yards.

“We have a lot of talent, but we got to get them to play as a unit, and that’s on us as coaches,” Rivera said of Washington’s defensive line. “We have to make sure the things that we’re doing, things that we’re creating for them are things that they can work and go out and function and be a unit together.”

Allen, a first-time Pro Bowl pick last season, wasn’t the first to expose Washington’s myriad problems on defense. He just did it better than the others, and Buffalo’s second-ranked defense stifled Washington.

The heroics of quarterback Taylor Heinicke were shrouded by mistakes Sunday; he threw for two touchdowns and ran for a score but also tossed a pair of interceptions. Tight end Logan Thomas lost a fumble in the first quarter.

Washington failed to score on its opening drive, as it has in 18 of its past 19 games. Since the start of last season, it has scored only seven points on its first possession and has allowed 57 to the opposition. Buffalo became the latest to pick up a quick seven points.

Heinicke admitted he was pressing at times with Washington trailing by three scores for much of the game.

“When you’re down by 20 points, you want to make something happen,” he said. “I just have to realize one possession at a time, one play at a time. And as long as we keep going down and scoring, we’ll be in the game. And pressing and throwing picks is definitely not going to help that.”

On his first interception, early in the second quarter, Heinicke initially targeted Adam Humphries, but he was covered so Heinicke turned to Terry McLaurin on the left side — as three Bills converged on him.

“I tried throwing the ball, and their safety came off of Logan and made a good play,” Heinicke said. “It’s things like that — when things break down, just be very smart with the ball. There’s big plays to be had, but at the same time, there are bad plays to be had. And I just got to eliminate that.”

The negative plays — on offense and defense — often came on third down. In the first quarter alone, Thomas fumbled after a nice catch on third and eight, and running back J.D. McKissic was flagged for offensive pass interference on third and two (negating a 16-yard catch by McLaurin). By game’s end, Washington had converted just 2 of 11 third-down attempts. Buffalo, meanwhile, had little problem securing first downs — thanks in part to its success on third down.

“I promise you: We’ll put the tape on, and we’ll see some mistakes, and we’ll sit there and say: ‘Man, we did that last week. We’re not learning,’ ” Rivera said. “. . . And that’s what my fear is. . . . I’m going to feel like we didn’t learn anything in the first two weeks.”

Through three games, Washington has one of the league’s worst third-down conversion rates against at 58.7 percent, and the offense has the worst conversion rate at 26.5 percent.

After Buffalo jumped to a 21-0 lead in the first quarter, Washington bounced back in the second, giving false hope of a turnaround.

Second-year running back Antonio Gibson broke loose for a 73-yard catch-and-run that ended with a dive inside the pylon for a touchdown. On the subsequent kickoff, the ball bounced off Washington linebacker Khaleke Hudson in coverage, then bobbled on the ground before Dustin Hopkins cradled it to recover his own kick.

With another chance to narrow Buffalo’s lead, Washington needed only five plays and 24 yards to find the end zone. Heinicke connected with Thomas on a 14-yard completion then dived across the pylon for a four-yard touchdown run on the next play to make it 21-14.

But hope soon fizzled as the defense — with missed tackles, minimal pressure, blown assignments and leaky coverage — failed to contain the Bills. On that long drive in the third quarter, Buffalo racked up seven first downs before Allen found Emmanuel Sanders for a five-yard score to make it 33-14.

“That was very disheartening because if you can make a stop, you feel like you have a little momentum — and we didn’t that,” Rivera said. “That was disappointing.”

As the wreckage continued, frustration mounted. Late in the game, Young stood next to defensive coordinator Jack Del Rio to seemingly vent — and promise that things would be different when Washington returns to Northern Virginia ahead of next week’s game at Atlanta.

“When we come back in the building, no bulls---ting,” Young recounted of the conversation. “If someone bulls---s, you let me know because I ain’t having that.”

But as Buffalo continued to trounce his team, Rivera stood silently on the sideline with his arms crossed. All he could do was watch.