COSTA MESA, Calif. -- Khalil Mack knew he was delivering an old cliché, but the Los Angeles Chargers All-Pro edge rusher went with it anyway.

“You can never get too high,” he said. “You can never get too low.”

A tired phrase, but entirely fitting for the Chargers, through an uneven 2-2 start to the season.

Mack, in his ever-so-even demeanor, appears unfazed by the early ups and downs.

“Whatever you put into it,” he said of the season’s expectations, “you’re going to get out of it.”

The Chargers put a lot into their roster over the offseason in an attempt to not only earn their first playoff bid in four seasons, but to win a conference title for the first time since 1994.

They revamped a porous defense by trading for Mack, signing cornerback J.C. Jackson and defensive linemen Sebastian Joseph-Day, Austin Johnson, and Morgan Fox. They strengthened an offense that was already ranked among the best in the NFL by selecting right guard Zion Johnson with the 17th overall pick and signing tight end Gerald Everett.

However, the level of return on their investments remains unclear, as the Chargers approach the season’s quarter mark on Sunday in a Week 5 matchup against the Cleveland Browns (2-2) at FirstEnergy Stadium.

“We’ve faced some adversity,” said running back Austin Ekeler, who led the NFL in touchdowns (20) in 2021, but was held out of the end zone until scoring three times in a 34-24 win over the Houston Texans during Week 4. “Which, in my opinion, is the best way to start a season because it’s going to tell you a lot about your team.”

They’ve oscillated between dominant -- five sacks against Raiders quarterback Derek Carr -- and lousy -- a 38-10 blowout loss to the Jacksonville Jaguars at SoFi Stadium.

“For like a game and three quarters we were playing really at a high level,” said head coach Brandon Staley, referring to a season-opening 24-19 win over Las Vegas and a Week 2 27-24 loss to the Chiefs. “Really high level.”

Behind quarterback Justin Herbert’s league-high 1,250 passing yards, the offense ranks ninth in the league, averaging 23 points per game. But the defense ranks 30th, allowing an average of 27 points per game.

“We ain’t played our best football yet,” safety Derwin James Jr. said, disappointed that they nearly allowed the Texans to wipe away a 20-point lead last Sunday. “There’s definitely room that we can get better and continue to grow.”

The Bolts’ roster is stacked with stars -- the most in the NFL, according to ESPN’s top 100 predictive player rankings -- but it’s also been ransacked by injuries.

“To lose a couple guys here and there and be able to replace them and have some guys that maybe weren't expecting to play a ton make some huge plays in some big-time games,” Herbert said, “that's great to see and we'll keep doing that.”

Herbert continues playing through pain after fracturing rib cartilage late in Week 2 against the Chiefs. He’s also been without standout wide receiver Keenan Allen since Week 1 (hamstring), and playing behind a makeshift offensive line. Veteran center Corey Linsley is dealing with a knee issue and left tackle Rashawn Slater underwent season-ending surgery to repair a torn left biceps.

Allen, the Chargers’ receptions leader since 2017, is considered “day-to-day” to return, according to Staley. Linsley, after missing Week 3, returned last Sunday in a 34-24 win over the Texans, and rookie Jamaree Salyer, a sixth-round pick from Georgia, has taken over for Slater.

“Poised, strong, assignment-sound,” Staley said of the rookie after his debut.

On defense, Jackson has been in and out of the lineup after undergoing ankle surgery in August, and edge rusher Joey Bosa was placed on injured reserve after undergoing surgery following Week 3 to repair a torn groin.

Jackson, for his part, said after Sunday that he was fully recovered and ready to forge ahead. “It felt really good to get a victory with my team,” he said.

Bosa will miss six-to-10 weeks, Staley said. And in the meantime, the Bolts have turned to a committee of players that includes veteran Kyle Van Noy, second-year pro Chris Rumph II and recently-signed Derrek Tuszka.

“Our edge players, all four of them, played at a high level,” Staley said after defeating the Texans.

Despite their uneven performances and injury woes, the Bolts remain in the thick of the race in the AFC West. At 2-2, they’re tied for second with the Denver Broncos, but behind the first-place, six-time defending division-champion Chiefs (3-1).

“We’ve dealt with a lot of adversity,” Herbert said. “And I thought we handled that pretty well. It's a long season.”