COSTA MESA, Calif. – The Los Angeles Chargers spent the offseason bolstering their roster in attempt to make a deep playoff, if not Super Bowl run.

But through a 1-2 start, which included splitting back-to-back division games against the Las Vegas Raiders (0-3) and Kansas City Chiefs (2-1), the Chargers suffered several injuries to key players, causing significant questions about the team’s trajectory as they prepare for a Week 4 game at Houston (0-2-1).

“It’s part of the NFL. It’s an attrition league and you have to be ready for it,” Chargers coach Brandon Staley said. “What you have to do is weather the storm and stay together. Then, make sure the guys are coming back as quickly as they can.”

The Chargers had a league-high eight players land in ESPN’s 2022 NFL rank, which predicts the top 100 players of the season. However, five of them, plus Pro Bowl center Corey Linsley, are dealing with significant injury issues.

Here’s a look at the most concerning situations.

Quarterback

It’s always of great concern when the franchise quarterback has an ailment, and for third-year quarterback Justin Herbert and his fractured rib cartilage, there’s no recovery in sight.

“This injury is going to be there for a while,” Staley said after a 38-10 loss to the Jacksonville Jaguars last Sunday. “If you guys know the injury, it’s not like it’s going to feel better next week or the week after that. This thing is going to be present for a while. He felt good today. We’re going to continue to manage it the best we can.”

Herbert, 24, has avoided admitting to any pain, saying only that he’s feeling “good.”

But former NFL quarterback Matt Hasselbeck, who suffered the injury during his 17-year NFL career, provided some insight into how Herbert might actually be feeling.

“I’ve had this injury and it stinks,” Hasselbeck said on Sunday NFL Countdown, adding that the causes for concern are multiple. “Those little jabs, or the big hits, or can he throw? But it’s not even just that. It’s using your cadence. You can’t hardly even breathe when you have this injury... everything is bothering you.”

Playing through the injury, Herbert completed 25 of 45 passes for 297 yards and a touchdown, with an interception and lost sack-fumble.

Perhaps most concerning for the recovery of the young Pro Bowl quarterback moving forward, however, is that he’ll be playing behind a cobbled-together offensive line.

Offensive line

The Chargers have recently invested in their line, prioritizing protection for Herbert over the last two years.

In 2021, they signed veteran center Corey Linsley to a five-year, $62.5 million contract. Then, they selected left tackle Rashawn Slater with the 13th overall pick.

Last April, they used the 17th overall pick to select right guard Zion Johnson.

The line played together one game, in a season-opening 24-19 win over the Raiders, before it started to fall apart.

Linsley left the game in Week 2 because of a knee issue, and was inactive against the Jaguars, though Staley said Monday that the ninth-year pro was improving.

“He improved really over the last three or four days,” Staley said. “Really hopeful that he’s back in practice this week.”

In a much more devastating blow, Slater tore his left biceps tendon against the Jaguars and will miss the remainder of the season.

“It’s going to be a tough loss for us,” Staley said about the Pro Bowl tackle. “But we’re going to make sure, over the next couple of days, that we put good contingencies in place, that we put a group out there that can really play together.”

Will Clapp, a fifth-year pro who spent the last four seasons in New Orleans -- where offensive coordinator Joe Lombardi served as quarterbacks coach during that time -- has stepped in for Linsley.

And at left tackle, Storm Norton took over when Slater left the game. Norton lost the starting job at right tackle to Trey Pipkins III during training camp.

Staley said it was to be determined how they will account for Slater’s absence moving forward.

“We’re going to look through that over the next couple of days,” Staley said, when asked how jobs would be filled moving forward. “That’s what we’re going to try and determine, moving forward, is not trying to make too many moves where there is going to be a lot of moving pieces, where guys could potentially be doing a lot of new things. We’re going to try and keep things as consistent as we can.”

The Bolts also have reserve linemen Jamaree Salyer and Brenden Jaimes.

Pass rush

Star pass rusher Joey Bosa will be sidelined indefinitely because of a groin injury, taking away what was considered among the league’s top pass-rushing duos.

With an offense that was ready to make a playoff run in 2021, much of the offseason focus was placed on defensive improvements.

The Bolts traded second- and sixth-round picks to the Chicago Bears to acquire pass rusher Khalil Mack to pair with Bosa, but -- after a promising start to the season -- it’s unclear when the duo will be on the field together again.

“It’s of the nature of not day-to-day. It’ll probably be week-to-week,” said Staley of Bosa, adding that he was uncertain if the Pro Bowl edge rusher would be placed on injured reserve.

Mack has four sacks this season, which ranks second in the NFL. Bosa had 1.5.

The Chargers have been developing second-year pro Chris Rumph II, who is likely to play an increased number of snaps with Bosa out, and they also signed veteran linebacker Kyle Van Noy over the offseason.

Van Noy worked with the inside linebackers throughout training camp, but is considered a depth player on the edge, if needed. He moved to the position after Bosa was sidelined.

Wide receivers

The Bolts’ receptions leader since 2017, Keenan Allen has now missed two games, but Staley expressed optimism that the five-time Pro Bowler is closing in on a return since suffering a hamstring injury in Week 1.

“I think that you should see him back in practice this week,” Staley said.

If Allen is able to return, it certainly would be a welcome sight for a position group that is quickly thinning.

The Chargers kept only five receivers on their initial 53-man roster.

They lost reserve receiver Jalen Guyton for the season, with the fourth-year pro suffering a torn anterior cruciate ligament late in the fourth quarter last Sunday.

The remaining healthy receivers: Mike Williams, a 1,000-yard receiver last season; second-year pro Joshua Palmer and DeAndre Carter, who was signed over the offseason as a return specialist but has provided an unexpected spark on offense.

Cornerbacks

The Chargers spent a premium on cornerback J.C. Jackson in free agency, signing him to a five-year, $82.5 million contract.

However, his short time with the Bolts has been somewhat mysterious.

Jackson underwent surprise ankle surgery on August 23 after feeling discomfort during practices.

He was inactive in Week 1, returned in Week 2 and played 100 percent of the snaps, then -- despite a nine-day break, was inactive again in Week 3.

Staley said there were no setbacks in Jackson’s recovery, but that the fifth-year cornerback was dealing with inflammation.

“Nothing structural. The wound is feeling fine,” Staley said. “Making sure that he doesn’t go out there and have something else happen. There was just some inflammation that we were taking a look at, and being cautious, looking at the long term.”

In Jackson’s absence, cornerback Michael Davis -- a starter the last three seasons, has started.