Chargers offense is coming up short because of failure to throw long

Justin Herbert possesses so much talent in his right arm that he is testing the very limits of the things his coaches can conceive.

Last week, Chargers offensive coordinator Joe Lombardi said he and his staff “have to continue to expand our imagination” when it comes to drawing up plays for Herbert and his abundant gifts.

Still, coming off a 27-20 loss Sunday to Minnesota, the Chargers are left pondering ways to reignite a potentially explosive offense that mostly has fizzled in losing three of four games.

Against the Vikings, Herbert’s longest play was a 26-yard completion to Keenan Allen midway through the fourth quarter. The Chargers had only one other play that netted as many as 20 yards.

“You can never spend enough time trying to access the deep part of the field,” coach Brandon Staley said.

The problem, Staley explained, is that defenses have made “a concerted effort” to keep Herbert from displaying his big arm. They continue to take away the deep ball, meaning the Chargers must execute over extended possessions.

“When you play against a quarterback that’s as gifted as he is and you play against skill position groupings like ours,” Staley said, “you’re going to try to force him to drive the field.”

Last season, Herbert emerged quickly as a rookie because of his ability to throw deep. The Chargers finished with nine touchdown receptions of at least 25 yards.

This year, they have only two such scores, both coming from Mike Williams in the same game, a 47-42 Week 5 victory over Cleveland.

Herbert ranks 23rd in the NFL in pass attempts of 20 yards or more, according to Pro Football Focus. Among others, that’s fewer than Jared Goff, Sam Darnold and Justin Fields.

Staley said the Chargers have penalty of plays each week designed to stretch defenses. The fact opponents aren’t allowing those plays to materialize is the riddle he and his assistants are trying to solve.

“If a team is going to say, ‘Hey, you’re not going here in the deep part of the field from an air-yard standpoint,’ ” Staley said, “what you’ve got to be able to do is create explosions from the run-and-catch game or from misdirection.”

It’s mostly a matter of being more imaginative, Staley said, in order to find the necessary space for the Chargers’ playmakers.

Defenses also are clamping down on Williams after he opened the season like an All-Pro. Williams totaled 31 receptions through five games but has 10 catches over the past four. He had 165 yards against the Browns but 137 since.

On Sunday, Williams dropped what would have been a touchdown catch in the final six minutes as the Chargers scrambled to come back. Earlier on the same drive, Austin Ekeler had a drop on what could have been a long gain.

“We’ve got to continue to get him involved,” Staley said of Williams. “We play better when Mike’s involved, that’s for sure.”

After Williams and Allen, the Chargers also have received little production from their wideouts.

Through nine games a year ago, Jalen Guyton averaged 21 yards on 24 receptions with three touchdowns. He had catches of 49, 70 and 72 yards. This year, he’s averaging 14.4 yards on 11 receptions with a long of 22.

Rookie Joshua Palmer showed his big-play potential with a leaping touchdown catch in Week 8 against New England. But he has made few other notable plays while being used somewhat sporadically.

On Sunday, both Guyton and Palmer dropped passes too.

“We do need to see some production from that third wideout spot …” Staley said, “so that people really respect that player out there, and we force them to defend everybody.”

Etc.

Staley said cornerback Michael Davis (hamstring) is expected to begin working his way back into practice this week. He also said he hopes safety Nasir Adderley (ankle) can resume practicing. Linebacker Drue Tranquill remains on the COVID-19 list. … The availability of all three players for the Chargers game Sunday night against Pittsburgh won’t be known until later in the week.