PALM BEACH, Fla. — The Chargers brought in perhaps their biggest offseason signing under the cover of darkness on a Friday evening. Of course a Jim Harbaugh-coached team would make an offensive lineman the secret weapon of its offseason plan.

Fresh off a Super Bowl with the Philadelphia Eagles, Mekhi Becton has the Chargers head coach already dreaming of what a retooled offensive front could look like.

“The run blocking is elite. Pass blocking as well, elite,” Harbaugh said of Becton on Monday, speaking at the NFL owners meeting in his first comments with reporters since free agency opened three weeks ago. “It’s just hard to get around him. Just start visualizing that size, that length on the right side of the offensive line with Mekhi there and Joe Alt.”

Needing to boost the offense around quarterback Justin Herbert, Becton’s addition could quietly be the offseason’s highest impact move. Harbaugh expects the 6-foot-7, 363-pound Becton to begin at right guard, where the former first-round pick played during the Philadelphia Eagles Super Bowl run. He will complement rising star right tackle Joe Alt, the 6-foot-8 former fifth overall pick.

With left guard Zion Johnson experimenting with a shift to center, it leaves a hole on the left side next to Pro Bowl tackle Rashawn Slater. Former starting center Bradley Bozeman, who re-signed on a one-year deal, recent free agent addition Andre James and returning reserve offensive lineman Jamaree Salyer would be in contention for the left guard position, Harbaugh said. Trey Pipkins III would “probably be the No. 1 guy,” the coach added when reminded of the returning starting right guard.

The Chargers entered free agency with the second-most cap space in the league but didn’t make many splashy signings to build on their surprising 11-6 finish in the first year under Harbaugh. During the first wave of free agency, the team re-signed 11 players, highlighted by star edge rusher Khalil Mack’s one-year, $18-million deal.

After a breakout season with the Chargers, defensive lineman Poona Ford signed a three-year deal with the Rams, a defection that will “leave a bruise,” Harbaugh admitted. The Chargers tried to ease the sting by adding defensive tackles Da’Shawn Hand and Naquan Jones.

With moves still turning in the background and the NFL draft approaching, the Chargers, led by general manager Joe Hortiz, haven’t rested.

“As Joe says,” Harbaugh said, “it’s a year-round thing.”

A comeback route from 30-year-old receiver Mike Williams energized an impatient fan base that was happy to see a familiar face during an otherwise conservative free agency period. Running back Najee Harris and tight end Tyler Conklin are the only other offensive skill position additions.

Williams’ return thrilled Harbaugh, primarily because of Herbert’s equally enthusiastic reaction. Williams set a career-best with 1,145 yards receiving in 2021, one year after the Chargers drafted Herbert sixth overall.

It might not be the only reunion in line for the Chargers, who could still look for reinforcements at receiver. Former Chargers star Keenan Allen remains a free agent after he spent last year with the Chicago Bears, and Williams posted a photo of him and Allen on his Instagram story last week with the caption “Run it back turbo.”

“Anything’s possible,” Harbaugh said when asked of Allen’s potential return. “That would be cool.”