Brock Purdy is writing some kind of story.
“Mr. Irrelevant” from the 2022 NFL Draft — the nickname given to the last player selected — is anything but irrelevant entering the NFL playoffs.
The 49ers’ 23-year-old rookie quarterback is one of the NFL’s most remarkable stories this season, and he writes the final chapter in his improbable tome Saturday when 13-4 San Francisco plays 9-8 Seattle in the NFC wild-card playoff game. at Levi’s Stadium.
Raise your hand if you fired up your betting app before the season and placed money on an NFC playoff matchup between the 49ers and the Seahawks featuring Brock Purdy and Geno Smith at quarterback.
Purdy is the third quarterback the 49ers have played this season in what has become one of the strangest quarterback roller coasters in memory.
Trey Lance, coach Kyle Shanahan’s pick as franchise coach, started the first two games and was lost for the season with a broken leg in Week 2.
Enter Jimmy Garoppolo, the veteran who despite leading the team to a Super Bowl three years ago was seemingly unwanted by the franchise, which brought him back for 2022 as a backup. Garoppolo played well, perhaps saving the team’s 7-3 season as a starter, until he suffered a broken foot in December. 4.
Enter Purdy, a postseason three-stringer from Iowa State.
All he’s done is lead the 49ers to wins in their last five regular-season games, completing 67.1 percent of his passes for 1,374 yards with 13 TDs to just four INTs and a 106.3 rating.
Raise your hand if you bet the 49ers are 9.5-point favorites to win a playoff game with Brock Purdy at quarterback.
What a STORY.
It’s a story that has drawn attention to — and comparison to — a Hall of Fame quarterback who authored one of the greatest improbable journeys in NFL history, Kurt Warner.
Surface comparisons are straightforward. Warner is an Iowa native who played his college ball at Northern Iowa and, when passed over by the NFL, became a star for the Iowa Barnstormers in the Arena Football League before eventually carving out an improbable NFL career that included a Super Bowl.
Warner, an NFL Network analyst who now lives in Arizona (where Purdy is from), has been following Purdy’s journey closely and smiled.
“It’s been fun watching Brock’s journey,” Warner told The Post on Friday. “I was overlooked and he was overlooked to a degree, because he was picked so late [No. 262 overall].”
Since the NFL-AFL merger in 1970, nine backup quarterbacks have led their teams to championships. Among that group are Hall of Famers like Warner.
While she fully embraces Purdy’s journey, Warner wants everyone to “sit back and let him write his own story.”
“Tom Brady when he won his first Super Bowl was not the Tom Brady we know now, the greatest of all time,” Warner said. “He had a good team, he was throwing for 150 yards  in the [first] Super Bowl and a TD in the playoffs that year. He could be Tom Brady.
“We’ll know who Brock is four or five years from now. Right now, he doesn’t have to be the next Tom Brady, he doesn’t have to be the next Kurt Warner. Just go do your thing this year and embrace the moment.
“Eventually, we’re going to start to see, can Brock Purdy be a franchise quarterback, can Brock Purdy be an All-Pro, can Brock Purdy be a Hall of Famer? We’ll see along the way. We don’t need to see that now.”
Right now, Purdy is simply the most remarkable success story in the NFL. And he has the moxie of someone who thinks he belongs and the numbers to back it up.
“It doesn’t seem like it’s too big for him,” Warner said. “And that’s what excites you. If he does that now, maybe he’ll have a chance, maybe he can be one of those guys.”
When he takes the field Sunday, Purdy will be the lowest-drafted rookie quarterback to start a playoff game — at 110 picks.
Since 2010, according to ESPN, rookie quarterbacks are 2-9 in playoff games. Do you think Purdy cares about that statistic? Here’s something that matters more: The 49ers averaged 22.6 points before Purdy started and are averaging 33.5 points in his five starts.
Maybe more magic awaits. No rookie has ever led their team to a Super Bowl.
With his career over, his Super Bowl title and his Hall of Fame jacket hanging in the closet, Warner wrote a best-selling book about his journey that has since been turned into a movie.
Purdy doesn’t have a publisher yet, but he’s writing away. With his mind, his moxie and his right hand.