COSTA MESA, Calif. -- He starts every morning with a cup of hot coffee he takes with him to the Los Angeles Chargers' training camp facility.

"Nothing cold in the Staley household," Chargers coach Brandon Staley says. "It gets me in the right focus on my way in early."

Focus is important, especially now as this season turned to one of stress, and so the hot coffee is there, along with Staley's unwavering optimism.

"I really love doing this," he said. "I feel like nine games in, I have a pretty good sense of who we are as a team, and where we are, where we need to go. That's a good thing."

The season started out with wins over the Washington Football Team, Kansas City Chiefs, Las Vegas Raiders and Cleveland Browns en route to a 4-1 start. The Chargers made waves with aggressive fourth-down calls and exemplary play from second-year quarterback Justin Herbert. Then came two losses to the Baltimore Ravens and New England Patriots before a win over the Philadelphia Eagles, when everything seemed right again, only to fall back with a loss to the then 3-5 Minnesota Vikings.

And now three starters -- linebacker Drue Tranquill, defensive tackle Jerry Tillery and defensive end Joey Bosa -- are on the reserve/COVID-19 list and potentially out for Sunday night's game against the Pittsburgh Steelers at SoFi Stadium (8:20 p.m. ET, NBC).

Tranquill (who missed the Vikings game) and Tillery say they are vaccinated, so if both test negative twice more than 24 hours apart and are symptom free they can be cleared to return. Bosa is reportedly unvaccinated and said to be a close contact, so if he tests negative after a five-day quarantine, he, too, could be cleared to play just in time for Sunday night's game.

The Chargers need Bosa, who leads the Chargers with 5½ sacks and leads the league with three strip sacks.

All, potentially, is not lost and Staley is optimistic. Even at 5-4, the Chargers have a 66.9% chance to make the playoffs according to FPI even with the recent 1-3 stretch. They are a half-game behind the Chiefs and currently have the head-to-head tiebreaker over them and the 5-4 Raiders, setting up a potential AFC West-deciding showdown with Kansas City on Dec. 16.

But in the Vikings game, Staley wasn't as bold on fourth down as he has been most of the season, most notably in the Browns and Chiefs wins. With 4:40 remaining and down 27-17, the Chargers faced fourth-and-2 from the Vikings' 6-yard line. Staley, surprising just about everyone, decided to kick, taking what he said was a sure three points from a 24-yard field goal and make it a one-possession game. Still, they had to get the ball back and score, which they weren't able to do.

"I just felt like the certainty of points was too good to pass up," Staley said after the game. "Our kicker was kicking well. I just felt like, defensively, that we could get a stop. It was still going to be a one-possession game regardless. I just really wanted to make it a certain one-possession game."

It could have worked, as going for it on fourth down anywhere on the field has been his signature move. One he has crafted carefully with his young staff through analytics and has resulted in the Chargers going for it 17 times on fourth down (tied for fourth in the NFL) and converting 11 of them, including seven of their first eight.

"We have established a good way of playing, a good way of operating on a day-to-day basis," he said. "Setting high expectations for performance that everybody understands."

Center Corey Linsley is new as well, after spending six seasons with the Green Bay Packers. He shares Staley's unceasing optimism.

"Just knowing that we are going to have these inconsistencies are going to come up," he said. "Now we can have answers to them. The more we can do that, the less these inconsistencies are going to come up. ... I feel like there's such a small margin for error in this league."

It's the NFL and with a win over the 5-3-1 Steelers, who are just ahead of the Chargers in an extremely crowded AFC playoff race, the Chargers would likely be talked about as a playoff lock again, like they were when they two games better than the Chiefs after Week 5.

"We're halfway," Staley said. "Past halfway now and we've given ourselves the chance to compete. But we have to get to work, we have to improve and that's also on my mind. When I wake up, it's how much we need to improve and that's where I've been spending a lot of my energy."

There and at the coffee shop -- one is even in the facility for easy access.

"I made a pledge to my wife that I make sure its not too much," Staley said "I'll transition to tea every now in then."