Joey Bosa held out of training camp for more than a month, taking an aggressive stance in contract negotiations.

But that was before his rookie season in 2016, after the Chargers selected the Ohio State standout with the third overall pick in the NFL draft.

Four years later, as Bosa enters the final season of his rookie contract, no such tactic was necessary.

The Los Angeles Chargers recognized Bosa's importance to the organization, and more specifically, its defense.

On Tuesday, Bosa and the Chargers agreed to terms on a five-year, $135 million extension that includes $102 million guaranteed. That's the most guaranteed money for a defensive player in NFL history, surpassing the previous record mark of $100 million set by Cleveland Browns outside linebacker Myles Garrett two weeks ago.

Bosa was scheduled to earn $14.4 million this season, but his new deal also guarantees $78 million at signing.

"It makes me feel good, Joey's tied down for a little while and we know he's going to be a Charger," Chargers coach Anthony Lynn said. "We're all excited about that."

Bosa, who earned the largest contract ever awarded by the Chargers and became the first player in franchise history to agree to a deal worth at least $100 million, will continue as a cornerstone of the defense for the next six seasons.

In four seasons, Bosa has 40 sacks and is averaging 0.8 sacks per game, ranking fourth in the NFL. He also has the second-highest pass rush win rate among qualified pass-rushers since the start of 2017: Bosa beats his block within 2.5 seconds on 27% of his pass rushes, according to ESPN metrics powered by NFL Next Gen Stats.

Last season, Bosa produced 11.5 sacks and led the NFL with 24 pressures on third down.

Lynn identified Bosa, who turned 25 this month, as a player who could continue to help the Chargers long into the future. However, the fourth-year coach said he remained mostly removed from contract negotiations.

"When you get down to the dollars, I try to stay out of that," Lynn said. "It's my job to build these players up and make them feel like Superman, but when they want to get paid like Superman, I kind of step back."

Bosa's extension adds to a growing list of investments general manager Tom Telesco made in the defense this offseason.

In free agency, the Chargers signed All-Pro cornerback Chris Harris Jr. and veteran defensive tackle Linval Joseph to two-year, $17 million contracts.

Then, after selecting quarterback Justin Herbert with the sixth overall pick in April's NFL draft, the Chargers traded up to make a second first-round selection, snagging Oklahoma linebacker Kenneth Murray with the No. 23 overall pick. The rookie is expected to contend immediately for a significant, if not starting, role.

Despite Bosa's new deal, questions remain about the long-term look of the defense.

Defensive end Melvin Ingram III, Bosa’s pass-rush counterpart, is entering the final season of his four-year, $64-million contract and defensive back Desmond King II is also going into the final season of his four-year, $2.7 million rookie deal.

A day before Bosa agreed to terms, Telesco declined to discuss any specific contract negotiations.

However, despite a probable salary cap drop in 2021 due to financial effects caused by the coronavirus pandemic, Telesco expressed confidence about the Chargers' cap situation moving forward.

"We're set up pretty well looking into the future, even though we do have players that we still would like to extend," Telesco said. "We're going to be just fine and be able to do what we want to do."

Receiver Keenan Allen, tight end Hunter Henry and center Mike Pouncey are also entering the final seasons of their contracts.

It's anticipated that the Chargers will reach more agreements before the start of the season.

In the meantime, Bosa's arrival at training camp, along with his new deal, comes with a sense of relief.

"It's one less distraction you have to deal with," Lynn said. "Any time you can do that, I think it's great."