COSTA MESA, Calif. -- It was nearly two weeks after his team's final game when Los Angeles Chargers general manager Tom Telesco spoke to the media. His team had been relegated to the sidelines after losing to the Las Vegas Raiders on the last play in overtime in the last game of the regular season, which meant no playoffs for the third straight year and seventh time in eight seasons.

And that stung, and then some.

"Professionally, it was one of the most difficult defeats I've been through,” Telesco said Thursday. "I felt like we had enough to be a playoff team and get in to show what we could do, and it didn't happen."

Telesco said he remains a huge fan of coach Brandon Staley and his game plan, which included going for it on fourth down a lot (they converted 22-of-34 at a 64.7% clip, good for fifth in the NFL), sometimes even deep in their own territory. And judging by the opinions of players, Staley was right in doing so, even as the chorus grew louder from the bleachers that he should have played it safer.

To wit: Had the Chargers attempted field goals in Week 15 against the Kansas City Chiefs instead of unsuccessfully going for it on fourth down twice in scoring territory, they could have won in regulation instead of losing 34-28 in overtime. Had they not tried and failed a fourth-and-1 at their own 18 in the finale against the Raiders, they might not have lost 35-32 in overtime.

"I know that I can improve," Staley said. "But I feel like for my first year as an NFL head coach, I wouldn't change a lot. We're going to do the best we can to make the best decisions that we feel are going to give us that best chance to win. And I don't see that changing soon."

That's just fine with Telesco, who has been the Chargers' GM since Jan. 2013.

"I love the identity we play with," he said. "I really do. I support him 100%. I'm a big believer in using data to make decisions, as is he. It doesn't mean there isn't context involved in that."

"All these decisions, even though they're made in real time, there's research involved in it prior to the game. ... Brandon is not a robot, but with decisions on the field you have to make quick decisions in real time. I thought that he did a really excellent job with that this year. He has my support behind that."

Staley has three young sons and moved them from Los Angeles to Orange County last offseason, with a lot of help from his wife, Amy. Moving a family while managing a new team in the pandemic was stressful. But Staley kept his focus on finding help for quarterback Justin Herbert, especially on the offensive line, as the Chargers drafted tackle Rashawn Slater out of Northwestern in the first round and signed center Corey Linsley as a free agent.

If Herbert was the striking force, Linsley was the glue that held the line together. He, too, approved of Staley's fourth-down aggressiveness, saying "it gives us a huge boost of confidence."

The offense was not the problem. The Chargers were fourth in the league in scoring, averaging 27.06 points per game, and in expected points added (plus-116.4), behind only the defending Super Bowl champion Tampa Bay Buccaneers, the 13-4 Green Bay Packers and the Chiefs. But defense was another story.

The 9-8 Chargers finished last in third-down conversions allowed (49.5%), were tied for 29th in points allowed (27.0) and 26th in expected points added (minus-80.49). They allowed 138.9 yards per game on the ground, third-worst in the league and the most they've allowed since 2003.

And that, Telesco said, "is my responsibility to get that fixed.

"We just didn't play our best when our best was needed. I'll take the responsibility that our defense did not play up to the expectations that we had for them. I overestimated where we may be with that because I love the scheme. I love the system and I love the coaching staff. I we had gotten a little bit more, we would probably still be playing."

But they're not. Still, there's a belief that Staley has changed the culture of the Chargers, who appear to be on the cusp of something special.

Herbert couldn't have been more spectacular in bringing his team back in the fourth quarter of the Raiders game, erasing a 15-point fourth-quarter deficit to force overtime, converting five fourth-down conversions and throwing a 12-yard touchdown pass to wide receiver Mike Williams on the last play of regulation.

Telesco also credited Staley, who spent long hours getting to know and counsel Herbert, for his quarterback's improvement from a stellar rookie season. Herbert completed 65.9% of his passes (443-for-672) for 5,014 yards (second in the NFL behind Tom Brady) and 38 touchdown passes (third behind Brady and Matthew Stafford).

It was Staley's insistence on communication that led Herbert to stay around late after practice on Fridays just for talks with Staley and a few extra throws to receivers who also stayed behind. Herbert said Staley was crucial to his development as a clutch quarterback.

"We never quit," Herbert said. "That offense that went out there, we were in the huddle together. We believed in each other."

Receiver Keenan Allen, who caught 106 passes for 1,138 yards, agreed with Herbert's assessment of Staley.

"I think we're transitioning into a winning organization," Allen said. "[Staley] is building a lot of confidence in the culture and the coaching staff. We just have to be ready and do better next year."

And he wasn't the only one.

Said defensive end Joey Bosa, "I see a very bright future with a lot of young talent. I see a group that was in their first year in a system. It's a pretty complex system. It's going to take a while to master. The fact that we had the year that we did, which was a pretty successful year in my books. I'm pretty happy with it."

"We have his back," said safety Derwin James Jr., who made the Pro Bowl after a 118-tackle season. "I run with my coach. That's my coach. We support all of his decisions."