INDIANAPOLIS -- Eighteen weeks ago, quarterback Philip Rivers appeared to have packed a few more turnovers in his belongings during his move from California to Indiana.

Rivers, making his first start with the Indianapolis Colts, threw two interceptions, including one in the fourth quarter of a Week 1 loss at Jacksonville.

The reaction outside the Colts organization was swift.

• That's what happens when you bring in a player on the decline of his career.

• What did you expect from a 38-year-old player coming off a 23-turnover season?

• Now you see why the Chargers didn't want to bring Rivers back.

Criticism of Rivers was warranted at the time, as the player the quarterback-starved Colts gave $25 million to for one season played a part in what turned out to be the Jaguars' only victory of the season.

"Philip's first month was bad," ESPN NFL analyst Dan Orlovsky said. "First month was somewhat scary because in moments when he didn't need to panic, he'd panic and throw silly interceptions without pressure. That was concerning."

It wasn't first-game jitters with a new team after spending the first 16 years of his NFL career with the Chargers.

It was a month -- well, two games for Rivers.

He threw two more interceptions, one that was returned for a touchdown, and was responsible for a safety in a Week 5 loss at Cleveland.

But through it all, coach Frank Reich, despite knowing he put his reputation on the line, never wavered in his confidence with Rivers, even with constant questions on whether the coach should bench the veteran in favor of backup Jacoby Brissett.

Rivers never flinched, either.

He brought stability to the position that had been unsettled since Andrew Luck retired in August 2019. Rivers had the third-highest completion percentage (68%) of his career. He threw nine fewer interceptions than he did in 2019. And most importantly, he did what the Colts brought him to Indianapolis to do: lead them to the playoffs. The Colts play at Buffalo on Saturday (1 p.m. ET, CBS).

"That first Jacksonville game came and it was just bad, bad interceptions," ESPN NFL analyst Matt Hasselbeck said. "That's not what I think of when I think of Rivers. But he always had Frank in his corner. I think that's important. The way Frank said over and over again, 'Philip is our guy,' goes a long way."

The Chargers respected what Rivers did for them, but they also knew it was time to turn the page.

The quarterback flirted with retirement before deciding to play a 17th season. Rivers said he didn't pay attention to the critics. The competitor in him didn't want his career to end as one of the NFL's interception leaders in his final season.

And there was the desire to try to make a run at a Super Bowl, which is something that has eluded Rivers.

"Some of [the criticism] was warranted," Rivers said. "I think when you are 38 and you come off of a 20-interception season and you're changing teams, then the skepticism is warranted and understandable -- the criticism is understandable. I think in some ways understandable, but yet at the same time, mentioning again some of the good ball that was played last year minus some of the disastrous plays and turnovers, I knew I still had it left.

"I think the way I've always handled all of that is -- again, I never tried to shy away from it. It's part of what we signed up for playing quarterback in the National Football League."

The Colts had Reich and something Rivers rarely had with the Chargers, an established offensive line.

The line, led by Pro Bowl selections Ryan Kelly and Quenton Nelson, is one of the best in the league. That was needed for Rivers, whose lack of speed would never have him anchoring a relay race. He was coming off back-to-back seasons when he was sacked 32 and 34 times, and he had been sacked at least 30 times in a season on nine different occasions.

Reich and offensive coordinator Nick Sirianni built their passing game around Rivers. There weren't any deep drops in the pocket that had him holding on to the ball too long. It was more about intermediate and quick throws while also taking advantage of a strong running game. The 2.52 seconds Rivers averaged in getting rid of the ball ranked as the fifth fastest in the league this season, according to NFL Next Gen Stats.

"The offensive line protection has been outstanding. I think it always starts there," Sirianni said. "This is one of his lowest sack rates, too, and Philip [gets] a lot of that credit, too, because he gets the ball out on time and he knows where he's going with the football, and he's smart."

As valuable as Rivers' throwing is, the experience he brought has carried significant weight. His leadership inside the locker room was immediately felt when he got the offensive players together for workouts so they could get to know each other, as they didn't have an offseason program due to COVID-19.

There isn't a defense Uncle Phil, as his younger teammates like to call him, hasn't seen during his career. He spends time during games calling out coverages by the defense.

"If you get him, it'll be one time and one time only,” veteran pass-rusher Justin Houston said. "You're not going to get him with the same pressure; he's definitely going to figure it out. He's a coach on the field. To have that experience, it's amazing. That's a reason why we're in our situation."

Reich knew all this about Rivers. He was Rivers' quarterback coach for a season and offensive coordinator for two seasons with the Chargers. The current quarterback and former quarterback broke down film together, talked the game and game-planned together. It wasn’t just a coach-player relationship; it was a friendship. That's why Reich told general manager Chris Ballard and owner Jim Irsay he was interested in signing Rivers. And that's why Reich spoke up the loudest about sticking with Rivers when he started the season off slowly.

"Confidence is the easiest thing to lose and the hardest thing to get back, and what happens when you have a coach like Frank, your confidence doesn't go away," Orlovsky said. "When a coach is believing in you and keeping it real with you and trusting you, that's humongous. It's almost like parenting with your children. When you consistently show your children you'll trust them, they believe in themselves a little bit more."

Not all coaches would do what Reich did with Rivers. Patience, especially when it appeared the quarterback was a weak link on a team expected to make the playoffs, might not have been there. They could have be more inclined to shut the book on Rivers and admit their failure in bringing in an aging veteran.

Reich's prior relationship with Rivers helped him stay committed to the quarterback.

"It absolutely factored into it," Reich said. "That's part of the reason he is here -- the history that we had together, the belief and confidence that I have in him that he's got that mental and physical toughness to overcome. I've seen it time and time again. ... I was just confident that whatever minor setbacks he had along the way, that they were minor. I was confident that when it was all said and done, that the overarching trajectory of what he would do this year for our team would be an arrow up and see him getting better and better, and I believe that has come to fruition."