LOS ANGELES -- John Ramsdell was the man at Philip Rivers' side when Rivers first became a starting NFL quarterback. One of Ramsdell's biggest contributions was a simple message that became increasingly profound over time, a mantra to which Rivers now clings: "If your whole happiness is based on whether you win a Super Bowl or not, then you have a chance to be a miserable person."

Ramsdell, the Chargers' quarterbacks coach from 2006 to 2012, was trying to explain how championships are too fickle, random and serendipitous to define success.

Rivers didn't fully understand that idea until he began to experience it. Until he watched Marlon McCree come up with the game-clinching interception and fumble it away in the divisional round of the 2007 playoffs. Until he took the field with a balky knee and no running back in the AFC Championship Game in 2008. Until he stood helplessly on the sideline while Nate Kaeding missed three field goals in a three-point loss in the second round in 2010.

All those bad bounces, untimely injuries, special-teams gaffes and bewildering close losses -- all those moments that made the Chargers one of the sport's unluckiest franchises -- gave Rivers some nuance about the Super Bowl, legacies and the way we measure success.

It made Ramsdell's words resonate.

"Not that you ever settle," Rivers said with particular emphasis. "By no means am I saying I'm settling. It's not that. It's just that [a championship is] not going to define happiness for me at the end of day. Now, do I want us to win one as bad now as ever? Yes. For sure. But I don't lose sleep at night. It's not going to be something that makes me go, 'Gosh, man,' or not at peace. It won't be that. That won't be the case."

Rivers is 37, coming off what might be his best season and staring at what might be his best opportunity. He ended 2018 with a 105.5 passer rating that was tied for his highest since becoming a starter in 2006. Despite struggling in stretches over the final three weeks, he finished the regular season within the top 10 in touchdown-to-interception ratio (2.67), completion percentage (68.3) and Total QBR (70.2).

More importantly, Rivers guided a 12-4 Chargers team that finished with the NFL's sixth-best scoring offense and eighth-best scoring defense.

2004's first-round QB class Stat Manning Rivers Roethlisberger Career Yds. 55,981 54,656 56,194 Total TDs 367 377 382 Total INTs 239 178 190 Playoff record 8-4 4-5 13-8 Super Bowls/Wins 2/2 0 3/2

After missing the playoffs in seven of the past eight years, and losing a combined 23 games in two of those seasons, Rivers has a legitimate chance to go further than he ever has. He could win a ring and be underappreciated no longer. He could put himself on par with Ben Roethlisberger and Eli Manning, champion quarterbacks who were taken in the same draft and have comparable, if not worse, numbers.

"That would change the dynamic," said tight end Antonio Gates, the longest-tenured member of the Chargers. "When you think of any other quarterback that came in his class, the first thing that stands out between all of them is just that they won. That's it. You don't say anything else but, ‘They won.' … But from a standpoint of just performance, it's like John Elway and Dan Marino. Philip is more like Dan Marino. ... "

Nick Hardwick, the Chargers' center from 2004 to 2014, watched many players come into his locker room and quickly develop a new perception of Rivers. He was far nicer, more modest than they ever imagined. Rivers' fervent competitiveness and relentless trash talk earned him a sour reputation throughout the league.

"And I think now, for the first time, the year that he's having has shown America what we've always known about Philip -- he's tough, he's gritty, he's resilient, and he does everything right," said Hardwick, now a sports talk radio host in San Diego. "... He's everything you would ever want."

Rivers is the man who won't go down, the one constant for a Chargers franchise that had been in constant disarray.

Philip Rivers' fieriness often belies how much he cares about his teammates. Mark Konezny/USA TODAY Sports

In January 2008, he faced the undefeated Patriots in the semifinal round with a torn ACL and without Hall of Fame running back LaDainian Tomlinson and nearly pulled out a victory. In 2010, he led the league in passing while quarterbacking a team that was forced to use a record-tying 74 players because of injuries.

He was deemed finished after playing behind inferior offensive lines and throwing a combined 35 interceptions from 2011 to 2012, then won Comeback Player of the Year in 2013. He faced rumors about a potential trade to the Titans heading into the 2015 season, then threw for a career-high 4,792 yards. He tossed an NFL-leading 21 interceptions in 2016, while the Chargers placed an NFL-leading 24 players on injured reserve, then threw a combined 22 interceptions over the next two seasons.

In 13 years, with four different head coaches, he has led 30 game-winning drives in the fourth quarter or overtime.

"He's got an element of 'Rocky' to him," Hardwick said. "It's not pretty; it's just a lot of hard work, it's been a grind, he's been knocked on his ass a bunch, and he's gotten back up, and he's still standing in the ring."

Rivers is a father of eight -- soon to be nine -- and lives 70 miles from the Chargers' facility. His style, admittedly "still in the '90s," consists of khaki pants and 10-year-old cowboy boots. The vast majority of the players in his locker room are at least a decade younger, with few commonalities and nowhere near as much clout. But Rivers has tried his best to remain on equal footing.

"I always was conscious of not wanting it to be 'him' and 'us,'" Rivers said. "If that was the case, I would've been very bothered. And I don't think it has been. But I think being conscious before it ever could've gotten there was important to me. 'No, it's us. We. I didn't hit 25 [passes] in a row today. We hit 25 in a row.' Know what I mean?"

2018 NFL Playoffs Coverage From the wild-card round through Super Bowl LIII, ESPN.com has you covered.

• Full schedule, news, notes »

More NFL coverage »

Norv Turner, the former Chargers head coach who is now the Panthers' offensive coordinator, used to tell Rivers about the importance of adjusting to the new wave of players who would cycle in throughout his career.

Tomlinson has been replaced by Melvin Gordon. Receivers Vincent Jackson and Malcolm Floyd are now Keenan Allen and Mike Williams. And defensive stalwarts Jamal Williams, Shawne Merriman and Antonio Cromartie are gone, paving the way for Melvin Ingram, Joey Bosa and Casey Hayward. Rivers wanted his new teammates to share the same camaraderie he experienced with his old teammates. He wanted to "let their personality become the personality of our football team," rather than setting the tempo by himself.

"And that's what makes him so special -- being able to lead two different kinds of groups like that," Ingram said. "That's when you have a true leader -- when he can teach you how to lead."

Different Chargers break down the post-practice huddle on most days and Rivers has often implored others to take on leadership roles. He's on a perpetually active text chain with Gordon and Allen. During training camp, the two showed him how to find a free billiards game on his iPhone, sparking a summerlong competition. When they're playing cards, shooting hoops or talking nonsense, Rivers goes out of his way to be around.

"You can tell he tries," Gordon said, "and we know it."

Rivers used to let the little things bother him. He'd see a teammate relaxing on the couch and grumble about his laziness, deepening the divide with a new generation of players. Eventually, though, he loosened up. He learned to embrace the fun, easygoing, unselfish group that surrounds him. He learned to let go of the early days.

"One of my favorite parts of this game is being a teammate," Rivers said. "And in my mind I'm going, 'Don't lose your favorite part. Because your core's phasing out, you're going to lose your favorite part?' Naw."

Rivers encountered a defining moment in late September. It was Week 3, in a highly anticipated matchup against the cross-town-rival Rams, and the Chargers were down by two scores. Suddenly the voice in Rivers' head began to ring.

"Don't do it," he told himself. "Don't you dare do it."

Shortly after becoming the Chargers' coach, Anthony Lynn met with Rivers and stressed the importance of taking care of the football. It became a theme of every offensive meeting over the next two years, enough so that Rivers began to successfully fight himself against forcing his will upon games.

Before throwing two picks in each of his last three games, Rivers carried a 1.5 interception percentage that was on pace to be the lowest of his career. According to NFL Next Gen Stats, the percentage of throws Rivers has made into tight windows -- defined as those with less than one yard of separation between the targeted receiver and the closest defender -- has dropped from 18.9 in 2016 to 16.7 in 2017 to 15.7 in 2018.

Instead of forcing passes downfield, Rivers is mostly checking it down, averaging 7.61 yards per attempt on throws to his running backs, second-highest in the NFL.

"I know you have to make tight-window throws in this league, and he does that at a high level," Chargers quarterbacks coach Shane Steichen said. "But I think it's the jump balls, where there's two guys around him, to where it's like, 'Hey, let's not throw those up and just throw it out of bounds.' And he's been doing a heck of a job with that."

Rivers still has his moments. Like those interceptions on opening drives against the Chiefs and Ravens in Weeks 15 and 16, which put the Chargers behind early in big games. Or that other one late in the third quarter against the Broncos in Week 11, sparking a blown lead that still haunts him. Or that poor first half against the Broncos in Week 17, which included two interceptions within the game’s first 11 minutes.

Mostly, though, Rivers has stayed measured.

"Controlling what I can control," is how he described his approach these days, "and only making the plays that I can make."

Part of that comes from Rivers' maturity. Part of it is Lynn's approach of prioritizing the running game and avoiding turnovers. But the biggest reason for Rivers' increased efficiency might be the personnel around him, now good enough to thrive on its own.

The Chargers are loaded with weapons even without star tight end Hunter Henry, who could return for the wild card round against the Ravens. The receiving core -- of Allen, Mike Williams, Tyrell Williams and Travis Benjamin -- is as deep as any. So is the running back group, with Austin Ekeler and Justin Jackson sliding in behind Gordon, a two-time Pro Bowler. If the offense doesn't score, a defense with a menacing pass rush and a dynamic secondary can get the ball back.

The Chargers couldn't secure a bye and won't draw a home game. But they have a legitimate chance to go to the Super Bowl for the first time since 1995, when they lost to the 49ers. The Chiefs team that won the AFC West is vulnerable on defense. The Patriots might be too old; the Texans and Ravens might be too inexperienced.

"They've got everything that it takes to win," Hardwick said of the Chargers. "They've got a very intelligent quarterback, they've got all the athleticism you can want on offense, they have a strong offensive line, they have a lot of depth now -- which I think is a huge factor when you're talking about these huge playoff runs -- and they have the defense. And defense wins championships."

Dan Fouts never quite had that championship team around him. The Hall of Fame quarterback spent his entire 15-year career with the San Diego Chargers, garnering All-Pro honors on two occasions and leading the league in passing four times. But Fouts never advanced past the conference round from 1973 to 1987. Now his name is lumped in with others like Marino's, Jim Kelly's and Fran Tarkenton's -- great quarterbacks who never won The Big One.

With other offensive stars like running back Melvin Gordon (left), Rivers doesn't have to do all the heavy lifting for the Chargers. Harry How/Getty Images

"I'm reminded of it every year," said Fouts, now an NFL analyst for CBS. "It's always going to be there. It's always going to come up. But it's been 30-plus years where I've been in another career. I'm proud of my career, I'm proud of the players I played with. We gave it all we had every Sunday, and that's all you can ask for. People that have never been in the arena don't understand that, I'm sure. But those of us that have understand that that's what it's all about -- it's the effort given."

Rivers was asked whether his career would feel complete without a Super Bowl and was very careful about his answer.

"That's a hard one to verbalize," he said, pausing for a moment. Rivers feels a responsibility to live up to the expectations placed upon him, but not necessarily the added pressure of finishing the job. He said a championship "doesn't drive me" because prior success would not alter his work ethic. He said his fulfillment comes from the deliberate process of building a winning culture, and the relationships forged through it, not some faraway destination.

Rivers posted a QB rating over 100 in all but six games this season. In Week 12 against the Cardinals, he completed 25 consecutive passes, tying a record set by Ryan Tannehill. In Weeks 13 and 15, he led improbable, nationally televised come-from-behind victories against the Steelers and Chiefs. Along the way, Rivers joined Brett Favre and the Manning brothers as the only quarterbacks to make 200 consecutive starts.

Now, if these next four weeks go as planned, he could add a championship to an otherwise-sterling résumé. It could alter the dynamic of his legacy.

But maybe it shouldn't.

"I hope it's more than that," Rivers said. "I would prefer that they say, 'Gosh, the guy played with a great deal of passion. ... He was a competitor, no matter what. He fought 'til the end. And he was a heck of a teammate.' Those are the two things I hope that the game, and this team, can say. Now if they can tack on there, 'And he led us to the 2019 Super Bowl and we won it,' then heck yeah."