SANTA CLARA, Calif. -- In the minutes after the San Francisco 49ers had pulled off the biggest trade of the season, phones started ringing on opposite ends of the country.

At around 9:30 p.m. ET on Oct. 20 in the Bay Area, Niners general manager John Lynch had just hung up with Carolina Panthers general manager Scott Fitterer after agreeing to swap a haul of draft picks for running back Christian McCaffrey.

Lynch immediately dialed 49ers coach Kyle Shanahan to break the news that a player many in the organization thought was out of reach was now joining their roster of stars.

"We were both like, 'Holy s---, that's a lot,'" Lynch said, laughing. "But we got him."

In Charlotte, McCaffrey spoke briefly with Fitterer, who thanked him for what he'd done for the organization. Moments later, as the news began to spread, McCaffrey's phone rang again.

This time, it was 49ers tight end George Kittle on the other end. Kittle and McCaffrey had become friends a few years earlier after hanging out at several Nike events, and Kittle had been telling McCaffrey for the past couple of years that he was destined to be a Niner.

Kittle was yelling so loud that McCaffrey could barely make out what he was saying.The excitement was mutual. Even though McCaffrey didn't want to be traded, preferring to stay in the only NFL home he'd ever known and believing strongly in his responsibility as a team captain, if he was going to land anywhere else, he wanted it to be with the Niners, with the likes of Kittle, Shanahan, receivers Deebo Samuel and Brandon Aiyuk and left tackle Trent Williams as teammates. He'd also be playing just 13 miles from where he played college ball at Stanford.

McCaffrey stopped short of trying to steer a trade to San Francisco, but the Niners were at the top of his list of potential landing spots.

"I thought it would be fun to play with those guys," McCaffrey said. "I might have mentioned it to my agent once or twice."

When the deal finally came together after less than a week of intense negotiations, the Niners sent second-, third- and fourth-round picks in 2023 and a fifth-round pick in 2024 to the Panthers.

For the rebuilding Panthers, it was a logical move to add to their collection of picks. For the Niners, it was a season-changer.

At the time of the deal, San Francisco was 3-3 and struggling to find offensive consistency. It has won 12 straight since McCaffrey became the starter and now plays in the NFC Championship Game at the Philadelphia Eagles on Sunday (3 p.m. ET, Fox). McCaffrey did not practice Wednesday or Thursday due to a bruised calf but says there's "zero chance" he's not playing.

Before McCaffrey, the Niners ranked 19th in the NFL in points scored per game (20.3), 18th in yards per game (340.2) and expected points added (minus-0.05). After McCaffrey's arrival, the 49ers rank second (29.8), fourth (379.6) and second (7.4) in those categories, respectively.

"It's just what we expected and he's only exceeded all of our expectations," Kittle said. "He's just a fantastic football player."

Here's how the 49ers landed one of the most impactful in-season acquisitions in NFL history.

IN THE DAYS leading up to free agency every March, it's common practice for teams to restructure high-priced contracts to create space or simply be in compliance with the salary cap.

When McCaffrey agreed to convert $7,047,500 of his $8,037,500 base salary for the 2022 season into a signing bonus, it saved Carolina more than $5 million against the cap. Perhaps more importantly, it lowered his base salary to the bargain price of $990,000.

In the eyes of other teams, it made McCaffrey affordable if the Panthers decided to trade him. Though actual trade discussions didn't gain traction until October in the leadup to the Nov. 1 deadline, McCaffrey began hearing the whispers even before the Panthers planned to trade him.

"There were rumors in the offseason, so I didn't know what was gonna happen," McCaffrey told ESPN. "When all that stuff is going on, you just have to tune it out."

McCaffrey did, however, have conversations with Fitterer in which he made one simple request: be honest. McCaffrey wanted to be kept in the loop of where he might land.

Before McCaffrey could be traded, two things had to happen.

First, he had to prove he could return to form after ankle, shoulder, thigh and hamstring injuries that limited him to 10 combined games in 2020 and 2021. Second, the Panthers had to feel like they were falling out of contention.

It didn't take long for either scenario to materialize, as McCaffrey had 670 yards from scrimmage and three touchdowns in Carolina's first six games but received little help as the Panthers flailed to a 1-5 start.

Coincidentally, a McCaffrey trade became possible in Carolina immediately after the Niners paid an Oct. 9 visit to Charlotte. San Francisco cruised to a 37-15 win on a day when McCaffrey had 104 total yards and a touchdown. The next day, Carolina fired coach Matt Rhule.

With rumors swirling around McCaffrey, the Niners' interest was never in doubt. They'd loved McCaffrey in the 2017 NFL draft, and the Shanahan family knew the McCaffrey family well. Kyle's father, Mike, coached Christian's father, Ed, with the 49ers and Denver Broncos from 1994-2003.

Sure, the Niners had lost running back Elijah Mitchell to a knee sprain in Week 1, but this wasn't about adding a running back. It was about adding McCaffrey, specifically.

Lynch calls McCaffrey a "force multiplier" for his ability to not only produce but create opportunities for his teammates.

"Kyle and I both felt like Christian's a guy who can unlock this offense," Lynch said. "We were already really good. But this could be a difference-maker."

But before the Niners could fully dive in, Lynch and Shanahan had to play their usual game of optimism versus realism. When Lynch first presented the idea to Shanahan, he got the response he usually gets when he has a big idea.

"He said something like, 'Yeah, that'd be great, but there's no f---ing way,'" Lynch said. "And I was like, 'No dude, I think this can (happen), let's see."

Lynch and his staff quickly put together a plan to acquire McCaffrey, explaining to Shanahan how they could make it work financially and how it would affect the team's future NFL draft capital.

Before the Niners headed to the Greenbrier Resort in White Sulphur Springs, West Virginia, in between their victory over the Panthers and a Week 6 matchup at the Atlanta Falcons, Lynch began planting seeds with Fitterer.

Lynch was hopeful a deal could be completed quickly to avoid a bidding war, especially with the star-hungry Los Angeles Rams -- who'd swung big deals for cornerback Jalen Ramsey, quarterback Matthew Stafford and pass-rusher Von Miller in recent years -- looming.

"You see [Fitterer] and [say], 'OK, let's stay in touch on this thing,'" Lynch said. "So that's when it kind of started. But it was hard to get them really engaged. They were gonna wait right till the end."

BY THE TIME the 49ers arrived in West Virginia, the whispers about McCaffrey's availability had turned into full-blown chatter throughout the 49ers organization.

Shanahan's initial reticence was grounded in questions about the team's cache of draft picks. The Niners were already without a first-round pick in 2023 because of the move for quarterback Trey Lance in 2021. The Panthers had made it clear they wanted at least one first-round selection for McCaffrey.

The longer the trade talks dragged on, the more apparent it became that the Panthers might not get that kind of return for McCaffrey.

"It came on so fast at the end it just didn't seem that possible," Shanahan said. "Initially it's like, 'No, man, that's getting too greedy, that can't be the right move in the long run.' But then (Lynch) goes upstairs and they work on some stuff. They look at contracts, they look at the future, they come down, you get more answers. I'm like man, so it is possible. And then they do some more stuff and then now they have me sold."

That chatter, of course, made its way into the Niners locker room. Niners players had a similar initial reaction as Shanahan: McCaffrey would be an ideal fit, but how could it work?

Aiyuk said he thought there was "no chance" the Niners would get McCaffrey. Fullback Kyle Juszczyk and linebacker Fred Warner laughed at a teammate who brought up the idea, telling him, "That'll never happen."

Despite that cynicism, those who know how Shanahan's offense operates couldn't help but fantasize about the idea of adding another versatile player to an inconsistent offense.

"When you start talking about that kind of thing, it's pretty cool because the guys that have been here kind of felt like, 'Well, that fits,'" right tackle Mike McGlinchey said. "You hear some trades and stuff like that every time a name is out there and it's like 'Oh, the 49ers need him' and you can kind of tell the ones that are bulls--- and which ones aren't. And we're all sitting there and it's Christian McCaffrey and that kind of fits everything we do."

AS THE WEEK in West Virginia wore on, Lynch kept in touch with Fitterer, consistently checking in on what it would take to land McCaffrey, hopeful it would drop below a first-round pick. On Friday, Oct. 14, Carolina began to get serious.

According to multiple sources, the Broncos, in addition to the Rams and 49ers, made exploratory calls. Those conversations kick-started further negotiations.

So much so that, one day after Carolina lost to the Rams in Los Angeles on Oct. 16, Fitterer was compelled to sit down with McCaffrey and let him know the ball was rolling toward a trade.

"He just mentioned that stuff is going around and we don't want to trade you but if a good enough offer comes, we'll do it,'" McCaffrey said. "I just said 'I appreciate it, just continue to be honest with me.'"

As the Panthers' hopes of landing a first-round pick dwindled, they came to grips with having to settle for less but also had no intention of giving away McCaffrey, something Lynch said Fitterer made clear to him.

"It complicated it that there wasn't a first-round pick to be had," Fitterer said after the trade. "We had to figure out what's the equivalent of a first-round pick if that's the case ... It was a combination."

Once the price dropped below that first-round threshold, interest from the Rams and Niners, both of whom did not have a 2023 first-round pick, kicked into high gear.

BY OCT. 19, the Rams and Niners had emerged as the contenders for McCaffrey. By the next night, Fitterer could tell the urgency to strike a deal had hit its peak and asked each team for its best and final offer.

According to multiple sources, the Rams' offer included second- and third-round picks in 2023, a Day 3 pick in 2024 and/or running back Cam Akers. The Niners were armed with a fourth-round pick in 2023 that could sweeten the pot, something the Rams didn't have because they'd traded it to the New England Patriots for running back Sony Michel in August 2021.

San Francisco's offer of second-, third- and fourth-round picks in 2023 and a fifth in 2024 won out. It didn't take long for word to spread among 49ers players.

McGlinchey was about to leave a wedding rehearsal dinner at The Inn at Pasatiempo in Santa Cruz when he got word. Upon getting the news, he ran back inside, told his fiancée, Brooke, and other assembled friends about it as the offensive line group chat exploded in celebration.

"It makes everybody like, like, 'Holy crap, we got a shot,'" offensive lineman Daniel Brunskill said. "One of the best things about having great players is when they're playing well, when they're great teammates, when they're working hard, it elevates everybody else to want to do better and keep working. And so like, once you get that, it's just like, 'Hey man, we got a shot to win this thing.'"

FOR MCCAFFREY, THE days that followed were a blur. Hours after the trade, he was on a 7 a.m. flight from Charlotte to the Bay Area and on the practice field that afternoon. The previous night, he told Shanahan he wanted to play in that week's game against the Kansas City Chiefs, and he did, getting 21 snaps two days after his arrival.

After that loss to Kansas City, McCaffrey was a focal point of the game plan the next week against the Rams. In his first start as a Niner, he became the first player since LaDainian Tomlinson in 2005 and fourth player since the 1970 merger to throw, run and catch a touchdown in San Francisco's 31-14 win. He hasn't slowed down since.

It's tricky! TD pass to 🏈

📺 #SFvsLAR on FOX pic.twitter.com/9CcXXH3XU7

— San Francisco 49ers () October 30, 2022

As a Niner, McCaffrey ranks third in scrimmage yards (1,403), second in touchdowns (12) and fourth in rushing yards (900). His 10 regular-season touchdowns with the Niners tied the Chiefs' Theotis Brown circa 1983 for the most by a midseason acquisition in NFL history and his 1,210 regular season scrimmage yards were the most ever by a midseason acquisition.

Looking back at the week of the trade now, McCaffrey says it was such a whirlwind that he still hasn't had time to process the emotions that go with being traded from the only NFL team he'd ever known. He's put that aside until this season is over.

But McCaffrey has also made it clear that he views the trade -- and every slight that's followed since, including Pro Bowl and All-Pro snubs -- as motivation.

"Obviously, I took it personally," McCaffrey said. "When you get traded, it's one team saying we don't value you as much anymore and so we're going to get rid of you.' That's how I took it and that's what it is but I know it's a business. Just another chip on my shoulder and here I am."