Jay Gruden wants to see Josh Doctson earn his keep. (Toni L. Sandys/The Washington Post)

It was a stunning gaffe and a bad omen when the Washington Redskins’ first play of the 2017 NFL season — a deep-shot pass play that coaches and players had the entire offseason to script and rehearse — fell incomplete because wide receiver Terrelle Pryor Sr., streaking toward the end zone, couldn’t locate the ball in the sun.

It was the first of two near-certain touchdown passes that quarterback Kirk Cousins and Pryor failed to connect on during an afternoon of offensive futility Sunday that resulted in a 30-17 loss to the Philadelphia Eagles. Chalk it up to a still-developing chemistry between a quarterback and 6-foot-4 wide receiver who have been working together just four or five months.

“That is going to be the issue,” Coach Jay Gruden said Monday, after reviewing footage of a defeat that, for a fifth consecutive season, has landed the Redskins at the bottom of the NFC East heading into Week 2. “We just have to keep practicing. We have to do a good job of getting these guys on the same page and comfortable with what they can run.”

It is baffling that three weeks of training camp and four preseason games weren’t enough to identify at least one high-percentage, bread-and-butter pass play between the Redskins quarterback and featured receiver. It was equally puzzling, as Sunday’s season opener unfolded, that Gruden made no apparent effort to involve the team’s other projected leading wide receiver, Josh Doctson, in the passing game.

The 6-2 Doctson was deemed such a difference-maker coming out of Texas Christian that the Redskins chose him with their first-round pick in the 2016 NFL draft and, largely as a result, felt confident in letting veteran wide receivers DeSean Jackson and Pierre Garcon depart via free agency this spring.

As his passing game struggled Sunday, Gruden never turned to Doctson, who was on the field for just 20 of the team’s 63 offensive snaps and wasn’t targeted on a throw.

Asked Monday about the limited workload, Gruden said Doctson needed to “earn” his playing time.

“I don’t think it’s a readiness issue; I think he’s ready to go,” Gruden said of Doctson, whose rookie season was derailed by Achilles’ ailments. “I think it’s something more that he has to perform. He has to play well to earn more playing time. He hasn’t practiced a whole lot; last year, he didn’t practice a lot. This year, he has been in and out of the starting lineup a little bit. I think once he establishes himself as an everyday player, he’s going to get the reps, and he’ll prove that he is one of our top receivers. . . . But he has got to earn that right like everybody does.”

The passing game was among several Redskins weaknesses that the Eagles exposed and exploited Sunday.

Instead of building on its success last year, the offense (the NFL’s third-most productive in 2016, averaging 403.4 yards per game) regressed markedly, gaining just 264 yards. Cousins was responsible for three of the team’s four turnovers. And the running game contributed just 64 yards (Cousins accounted for 30 of those). Of the 13 runs by backs Rob Kelley and Chris Thompson, five lost yardage.

Gruden acknowledged Monday that he was surprised by the line’s struggles in both run blocking and pass protection but said that all five starters had a hand in it.

“It’s not like each individual played terribly,” Gruden said. “It’s just they all had mistakes or poor protection things at inopportune times. They will work at it and they will get better. They have to.”

Familiar problems persisted — slow starts, poor red-zone offense and poor third-down defense.

The defense allowed the Eagles to convert eight of 13 third downs and was slow to get going, letting quarterback Carson Wentz slip the grasp of two defenders and throw off-balance for a touchdown on Philadelphia’s opening drive. With size and elusiveness, the 6-5 Wentz bedeviled the Redskins’ front seven much of the afternoon.

Whether the question was about Cousins, running backs, receivers or defenders, Gruden insisted Monday that everyone needs to improve. But he provided few details on how that might happen over the three upcoming days of practice at Redskins Park before the team leaves for Los Angeles for Sunday’s game against the Rams, 46-9 opening-day victors over the Indianapolis Colts.

Gruden alluded to no changes in the lineup, although he did suggest that Doctson’s workload would increase.

Despite Jamison Crowder’s muffed punt Sunday and his value as a slot receiver, Gruden said he intended to keep the third-year wide receiver on punt returns. And he said he expected to alternate between starting cornerback Bashaud Breeland and Thompson, his valued third-down back, on kickoff returns.

“I think Breeland wants it,” Gruden said, asked if he is concerned about exposing a starting cornerback to injury on kick returns. “He has been wanting to be a kick returner for a while, so I’ll let him keep doing it. He has done well. He’ll be okay there. We just have to block for him.”

Gruden said there were no injuries to report from Sunday’s game, just bumps and bruises.

More Redskins:

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Steinberg: For bad season openers, there’s the Redskins and Browns, and then everyone else

Referee Brad Allen explains ruling on game-ending fumble TD

Best and worst moments from the Redskins’ season-opening loss