Only days before the NFL’s 53-man cutdown deadline in August, the quarterback now hailed as the San Francisco 49ers’ savior wasn’t even a sure bet to make their roster.

Brock Purdy, the last pick in the 2022 NFL Draft, had to beat a well-liked veteran whom the 49ers had just paid lavishly to be their top backup.

On March 11, 2022, the 49ers all but anointed Nate Sudfeld as their No. 2 quarterback by giving him a fully guaranteed $2 million contract. At the time, the 49ers intended to trade incumbent starter Jimmy Garoppolo to save salary-cap space and pave the way for 2021 first-round pick Trey Lance to take over.

The 49ers valued the 6-foot-6 Sudfeld because of his prototypical size, versatile skill set and obvious rapport with Lance. Sudfeld, a 28-year-old career backup, became a trusted friend and mentor to the raw but talented Lance while spending most of the previous season on the 49ers' practice squad.

As April’s NFL Draft approached, 49ers coach Kyle Shanahan and general manager John Lynch discussed the possibility of adding a third quarterback with one of the team’s final picks. In an interview with Bay Area radio station KNBR earlier this month, Lynch recalled Shanahan telling him, “I’d like to go get another young quarterback just to add into the mix. Let’s try to identify one later.”

Among the options was Purdy, a former three-star recruit who became Iowa State’s starter during his freshman year and maintained his hold on the job until he graduated. By then, he had completed more than two-thirds of his 1,467 passes and thrown 81 touchdown passes while helping carry a long-struggling Cyclones program to four straight winning seasons.

The 49ers scouted Purdy extensively. They interviewed Iowa State coach Matt Campbell and others close to him. Then quarterbacks coaches Brian Griese and Klay Kubiak peppered him with questions during a series of Zoom calls. The 49ers originally planned to target Purdy as their most coveted undrafted free agent, but they changed their minds during the draft after they were able to address more glaring needs at cornerback and along the offensive line.

The NFL awarded the 49ers a league-high five compensatory draft picks in 2022 for losing free-agent players, coaches or executives to other teams. The last of those, the final pick in the draft that bestows the “Mr. Irrelevant” title on one player each year, presented a perfect opportunity to splurge on a quarterback whose accuracy and experience intrigued the 49ers enough that they didn’t want to risk losing him to another team.

“We got there to Mr. Irrelevant, and I think we all just kind of looked at each other and said, ‘Why chance it?’” Lynch recalled.

The 49ers might have been the only team to value Purdy enough to use a draft pick on him, but even they had no inkling of what he’d become. On draft night, Shanahan described Purdy as having “traits very similar to Nick Mullens.” He envisioned Purdy developing in obscurity on the practice squad behind Lance and Sudfeld this season, not starting Sunday’s NFC title game in Philadelphia.

The 49ers’ perception of Purdy’s role began to change when he exceeded expectations during OTAs and training camp. He initially got only a few reps per day behind Lance and Sudfeld, but he turned heads by confidently zipping throws into tight windows.

“Every time he got his one or two reps in practice, he was decisive and got the ball to the right spot and did it aggressively,” Shanahan said Monday. “[He] never seemed unsure of anything, and so he kept earning more reps, and the more reps we gave him, the more he continued to look the same and didn't take any steps back.”

Those qualities eventually manifested in preseason games, too. Wearing a No. 14 jersey instead of his now familiar No. 13, Purdy engineered a game-winning drive in his debut against Green Bay. He opened more eyes the next two weeks by displaying more agility and athleticism than his college film suggested he had, by making plays with defenders in his face and by enduring crunching hits and popping right back up.

By then, the 49ers had seen enough. Mr. Irrelevant had beaten Sudfeld to become Lance’s primary backup.

“We were going to go into the year with [Purdy] as the No. 2,” Shanahan said in August. “And we were good with that because that’s what he earned.”

Then, out of nowhere, came a surprise announcement: Garoppolo was restructuring his contract and returning to the 49ers. Unable to get any draft picks for Garoppolo via trade but unwilling to let him go for nothing, the 49ers persuaded him to come back for one year as Lance’s backup.

Garoppolo’s return left the 49ers with more decisions to make. Now it wasn’t just choosing between Purdy and Sudfeld to be the backup quarterback. The 49ers had to decide if they would use a valuable 53-man roster spot on either quarterback as a third-stringer behind Lance and Garoppolo.

On Aug. 30, the 49ers cut Sudfeld with the hope that another team would sign him and offset part of the $2 million owed to him. That same day, they announced that Purdy had made the 53-man roster.

That show of faith in Purdy was an early sign that the 49ers believed they had uncovered a late-round gem. They could've rostered two quarterbacks and cut Purdy with the intention of signing him to their practice squad, but they couldn’t stomach exposing the seventh-round pick to waivers and giving a rival team an opportunity to claim him.

“It was pretty easy to see how Brock was coming,” Shanahan said Monday. “We knew we wanted to keep him on the roster and not risk him going to the practice squad, so it was a decision we had to make."

Placing that early bet on Purdy is one of the unsung yet pivotal moves that propelled the 49ers to within one victory of Super Bowl LVII. It would've been easy for Shanahan and Lynch to be stubborn about keeping Sudfeld after sinking $2 million into him. Or to prioritize retaining an extra lineman or defensive back on the 53-man roster over a rookie third-string quarterback.

Purdy has validated the 49ers’ faith in him by emerging as one of the NFL’s most remarkable feel-good stories. Since Lance suffered a season-ending right-ankle injury in Week 2 and Garoppolo broke his left foot in Week 13, Mr. Irrelevant has not only stepped into the limelight but also at times performed like the 49ers’ quarterback of the future.

The 49ers are 8-0 since Purdy took over for Garoppolo early in a victory over the Miami Dolphins. On his best days, Purdy has excelled in taking advantage of Shanahan’s innovative schemes and the 49ers’ collection of dynamic offensive weapons. At his worst, Purdy has avoided crippling mistakes and leaned on the 49ers’ elite defense and potent running game.

Shanahan calls Purdy’s success in taking care of the football “the No. 1 thing he’s done.” In six regular-season games and two playoff victories, Purdy has thrown for 16 touchdowns and four interceptions.

“To be able to be as good with the ball as he has while still making a number of the plays that he has, that’s definitely the thing I’ve been most impressed with,” Shanahan added.

In early December, just a couple of days after Garoppolo’s broken foot, the 49ers had a chance to make a waiver claim for Baker Mayfield after the Carolina Panthers cut him loose. The 49ers passed on Mayfield, another show of trust in Purdy that looks shrewder by the day.

Only six months ago, Purdy wasn’t a sure bet to make the 49ers' roster. Only two months ago, his best-case scenario seemed to be stepping in for Lance and Garoppolo and not messing up a good thing. Now he’s starting in the NFC championship game, and the 49ers are hoping this wild ride lasts a couple of weeks longer.