After the Washington Football Team’s disappointing defensive debut, it was fair to wonder whether the letdown was a one-week hiccup or a worrisome sign that the unit won’t live up to the immense preseason hype. During training camp, Coach Ron Rivera and players said they expected the unit to be strong, with defensive end Chase Young going so far as to say, “We could be the top defense in the league.”

After reviewing Sunday’s loss to the Los Angeles Chargers, Rivera blamed the defensive struggles on missed assignments. He pointed out that the team’s aggressive style requires players to play one assignment and avoid freelancing, because if even one of them is out of position, the whole unit can be affected. One example, he said, was a play in which the interior defensive line got a strong push but both ends made inside moves, which weakened the pass rush overall.

But Rivera was emphatic Tuesday in saying there was “no reason” for expectations for the defense to change. He highlighted that the unit still has a star-studded front four and linebackers who can run.

“I expect [the problems] to be fixed now,” Rivera said. “To me, it’s more of a matter of being disciplined. That’s the thing we talked about. This defense, the way it’s designed, it’s about accountability. You have a gap or assignment. You have a coverage assignment. You have to do it. If not, and they find it, we’ll know.”

But there is a statistical argument for why Washington could have a hard time maintaining the same level of defensive success that it achieved a season ago. In July, data analyst Dan Pizzuta published a chapter of the Football Outsiders Almanac titled, “Are We Expecting Too Much from This Defense?” In it, he noted Washington’s rank in the advanced metric Defense-adjusted Value Over Average (DVOA) improved from 27th in 2019 to third in 2020 — the eighth-largest jump of any defense since 1983.

He warned of the “Plexiglas Principle,” an idea introduced by baseball sabermetrician Bill James which states that, for any number of reasons, units that experienced massive year-to-year improvement tend to decline the following season. Of the past seven teams with steeper DVOA climbs than Washington, only two remained in the top 10 the next year — and three finished 26th or worse.

But Pizzuta found hope that Washington could defy the trend. Not only was the drop-off not as stark for the seven teams just below Washington in those rankings, but this defense also shares characteristics with those that maintained elite performance.

For example, from 2018 to 2019, the Tampa Bay Buccaneers, New England Patriots and San Francisco 49ers rocketed up the DVOA rankings. In 2020, Tampa Bay and San Francisco — two of the league’s 10 youngest defenses by snap-weighted age — finished in the top six again while New England, the league’s oldest defense, dropped to 26th. This year, by the same measure, Washington is the league’s fourth-youngest unit.

There are other causes for optimism, such as Washington addressing its struggles against No. 1 receivers last season by signing William Jackson III, a cornerback known for his ability in man-to-man coverage. Jackson had an interception in the red zone Sunday in his Washington debut.

But Pizzuta did point out that defensive performance is less stable than offensive performance on a year-to-year basis, for reasons that include the variability of turnovers. Talent alone, he said, doesn’t ensure a defense like Washington’s will finish atop the defensive rankings.

“Just to assume they’re going to be the best in the league . . . I don’t think that’s necessarily true,” he said during an interview in August. “They have a chance to be really good and a chance to be really average.”

Washington generated pressure on Chargers quarterback Justin Herbert on 12.2 percent of his dropbacks during Sunday’s loss, according to Pro Football Focus, which was the lowest rate in the league. The Chargers deployed several methods that appeared to be aimed at neutralizing the strength of Washington’s front — with chip blocks by non-linemen and max protection to fortify their pass blocking, and presnap motions and play-action passes to slow Washington’s pass rush.

Herbert didn’t have a super-fast release — his average time to throw of 2.7 seconds ranked 12th among passers in Week 1, according to NFL Next Gen Stats — but he only threw deeper than 20 air yards three times in 47 attempts, the league’s fifth-lowest rate.

This could be, in part, because Washington rarely forced him to look deep downfield. Los Angeles faced 19 third downs Sunday, and the average distance was 5.6 yards. When Herbert did have to make a downfield throw, on third and 16 during the last drive of the game, wide receiver Keenan Allen found a hole in the defense to convert.

On the play, no defender was within three yards of Allen. One problem could have been multiple players in the same zone, as Rivera mentioned during his news conference, but linebacker Jon Bostic said the blame fell on the players, not on coordinator Jack Del Rio.

“If 10 guys do their job and one guy doesn’t, understand it’s going to be an explosive play,” he said, adding: “It was a perfect call for us. We just didn’t execute.”

Now, the question is whether the defense can rebound in Thursday night’s matchup with the New York Giants — and whether it can live up to its billing as one of the league’s best units. For his part, Rivera is counting on a turnaround.

“I expect us to be better,” he said.