When Jimmy Garoppolo went down with a serious foot injury in Week 13 against the Dolphins, many figured the 49ers' season was over after previously losing Trey Lance to injury, leaving Brock Purdy -- the final player selected in the 2022 NFL Draft -- as the last quarterback standing. At best, the hope was San Francisco's top defense could help them grind out some wins if Purdy avoided giving the ball away.

Instead, the 49ers have picked up right where they left off, and might even be playing better, with "Mr. Irrelevant" under center. If Purdy accomplishes what people think he could, we're talking about one of the best underdog stories in sports history. 

"I'm surprised people aren't talking about it more honestly," 49ers linebacker Fred Warner told NBC Sports after the 49ers' Week 18 win. "It's something that is incredible for 'Mr. Irrelevant' to lead the team that we have into the postseason now on our way to try to earn a Super Bowl and knowing that we have full confidence in achieving that with him, it's truly, truly impressive."

Purdy has earned that praise from his teammates with his play over the last five weeks. Purdy isn't just skating by, he leads the entire NFL in touchdown passes, yards per pass attempt and passer rating since his first career start in Week 14. It's the highest passer rating by any 49ers player through the final five weeks of the regular season since Steve Young in 1996

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Brock Purdy NFL rankings since first career start in Week 14

Wins5T-1st

Team PPG

33.6

1st

Pass TD

11

T-1st

Yards per attempt

8.9

1st

Passer rating

119.0

1st

It's one of the best statistical starts by any quarterback in league history, too. He is the only QB since 1950 to win his first five starts with multiple touchdown passes in each game. He also has the second highest passer rating by any QB through five starts since 1950, between Kurt Warner and Patrick Mahomes. Any time you're in the same company as Warner and Mahomes, who both won MVPs in their first year as full-time starting QBs (not to mention Warner's Super Bowl MVP), you're doing something right.

Highest passer rating in first five career starts since 1950

Kurt Warner (1999)

131.4

Brock Purdy (2022)

119.0

Patrick Mahomes (2017-18)

116.3

Tony Romo (2006)

115.8

San Francisco is putting up big points in those games, too. The 49ers lead the NFL with 33.6 points per game in Purdy's first five starts. Only four QBs since 1950 have led their teams to more points through five starts. Warner, Daryle Lamonica, Mahomes and Deshaun Watson. The last time San Francisco scored this many points in the final five games of a regular season was 1994, the same season as its last Super Bowl title.

Highest team PPG in first five career starts by QBs since 1950

Kurt Warner

36.6

Daryle Lamonica

34.8

Patrick Mahomes

34.4

Deshaun Watson

34.0

Brock Purdy

33.6

You get the point. Combine the numbers and where he was drafted and this is bonkers. He doesn't deserve all the credit though as Steve Young told the San Francisco Chronicle this week.

"This is not a knock against (Purdy), this is just what he's asked to do," Young said. "But rate the degree of difficulty (on his passes), maybe on a scale of one to five. And see how many times it's over a three. And then go watch (Tampa Bay's) Tom Brady. Or these other offenses that are really struggling with no speed and no talent. And these great players — how many times do they have to do things that are three, four and five? It's amazing."

He obviously has a point. He's not dropping jaws with these throws. Kyle Shanahan's system and the talent around Purdy have certainly brought out the best in him, and deserve a lot of credit. However, it's amazing that a rookie, and the last pick of the draft, can do what he is asked to do this effectively -- lead the 49ers to a 5-0 record and the best scoring offense in the league, all while putting up the best passing numbers in football.

This stunning stretch now has Purdy in position to do things no rookie has ever done. On Saturday he will become the first rookie QB drafted in the seventh round or later (or undrafted) to start a playoff game since 1950. He could be joined on this list on Sunday by Skylar Thompson, and maybe even Anthony Brown, if Lamar Jackson and Tyler Huntley are unavailable. As the 262nd overall pick, we've never seen a rookie QB drafted that low start a playoff game. The last time any QB taken that low started a playoff game, regardless of rookie status, was 25 years ago with Doug Flutie.

Lowest drafted rookie QB to start playoff game since 1950

Brock Purdy (2022)

262nd

Skylar Thompson (2022)

247th

A.J. McCarron (2015)

164th

T.J. Yates (2011)

152nd

Dak Prescott (2016)

135th

Purdy also has a chance to go where no rookie QB has ever gone -- the Super Bowl. Oddsmakers are certainly paying attention. The 49ers are currently 10-point favorites against the Seahawks. No rookie QB has ever covered a double-digit spread in a postseason game. The previous high marks belonged to Ben Roethlisberger and Dan Marino. The 49ers are now even slight favorites to represent the NFC in the Super Bowl (+170), just ahead of the Eagles (+175), at Caesars Sportsbook.

Largest spread as favorite by rookie QB in playoffs since 1950

Brock Purdy (2022)

-10

Ben Roethlisberger (2004)

-9

Dan Marino (1983)

-8

Dak Prescott (2016)

-5.5

Let's just say it's not smart to bet against them. The 49ers finished with the top scoring defense in the NFL this season. They are healthy across the board (except quarterback). They have maybe the best offensive skills players in the entire league, a brilliant offensive mind in Shanahan and the offense is humming with Purdy. It all screams Super Bowl run, and a chance to rival 1999 Warner and 2001 Brady as some of the best underdog stories in league history. There's a lot of football to be played and the postseason brings a totally different level of pressure, but the table has been set for a storybook run here, one worth getting hyped up about.