NFL analysis: Best backup-to-starter quarterbacks in NFL history as Kirk Cousins heads to Las Vegas

Kirk Cousins arrived in Atlanta almost two years ago to the day as a $180 million quarterback, undisputed starter, and the new franchise cornerstone.
Then, the Falcons front office shockingly ripped up the script, drafting Michael Penix Jr. eighth overall barely a fortnight later and nuking the franchise's relationship with Cousins almost instantly.

The former University of Washington standout wasn't a complementary piece, nor a developmental body.
He was Cousins' replacement. And he arrived before the veteran gunslinger had played a single snap at Mercedes-Benz Stadium.

The organisation had already told him, in the clearest possible language, exactly what they thought of the investment.
The $180 million man was replaced as starter just 15 weeks into his deal, with the rookie who shocked everyone when he headed to Atlanta in the first place fully taking over.

Kirk Cousins heads to Sin City

An awkward season and a half followed, every loss a referendum on the relationship, every Penix rep breathlessly covered by Atlanta beat reporters, every press conference a tightrope walk around questions nobody could answer politely.

Cousins went 5-3 down the stretch last season when Penix tore his ACL, reminding everyone he still had something left in the tank, but he was released in February anyway.

Now he is heading to Las Vegas, where Fernando Mendoza, a Heisman winner, presumptive No. 1 overall pick, and the most hyped Raiders quarterback since Derek Carr, will take the keys, and Cousins will watch from the sideline.

Online betting sites could not have less faith in the Raiders' hopes for 2026, despite the addition of Cousins and the impending arrival of Mendoza.
The early Bovada NFL futures odds for next season position them as a +105 shot to not even reach six wins, let alone make the playoffs.

Here’s the thing, though: Kirk Cousins has lived this story before.
He knows how quickly a depth chart dissolves. In Washington, he unseated RG3, the No. 2 overall pick, seized his moment and earned $84 million fully guaranteed in Minnesota.

He is not a man stumbling into an unfamiliar role. He is the most dangerous kind of backup in football, one who already knows exactly how fast everything can change. And history is littered with proof.

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Brock Purdy

Brock Purdy was taping his wrists in the 49ers' training room in Week 13 of 2022, the 262nd player selected in that year’s draft, dead last, Mr. Irrelevant, preparing to replace not just any starter, but the two most significant quarterback investments in San Francisco's recent history.

Trey Lance was the cost of three first-round picks, a franchise-altering gamble that had consumed the front office's capital and credibility.

Behind him sat Jimmy Garoppolo, 31-14 as a starter, a Super Bowl appearance on his résumé, a reliable veteran whose presence had kept the Niners competitive for years.

Purdy was an afterthought behind two quarterbacks who represented everything the organisation had wagered on the position.

Then, the cutthroat nature of the NFL changed everything.

Lance fractured his ankle in Week 2, Garoppolo cracked his foot in Week 13, and Mr. Irrelevant was suddenly the most relevant man in the Bay Area.

Purdy was thrust into the limelight and proceeded to lead the Niners to a perfect 5-0 finish to the season with a 68.5% completion rate, 11 touchdowns, two interceptions, and a 119.0 passer rating that made NFL defensive coordinators look like they had not prepared for a player they had never considered preparing for.

Nick Foles

Nick Foles walked into Super Bowl LII carrying something heavier than a game plan.

He carried the weight of two franchises, St. Louis and Kansas City, that had looked him in the eye after his 2013 season, 27 touchdowns, two interceptions, the best quarterback rating in football, and decided he was not the answer.

He returned to Philadelphia and watched from the bench as Carson Wentz dismantled defenses all season, 33 touchdowns, seven interceptions, an 11-2 record that felt like a coronation waiting to happen.

Then the would-be MVP dragged himself to the sideline in Week 14 against the Rams, ACL torn, another touchdown already on the board, and suddenly the man both St. Louis and Kansas City had discarded was standing between Philadelphia and its first Super Bowl.

Do not sleep on what happened next. Foles orchestrated a 38-7 demolition of Minnesota in the NFC Championship, then delivered 373 yards, three touchdowns, and the Philly Special, a trick play that required the backup quarterback to catch a pass in the end zone on the sport’s biggest stage, against a Patriots team that put up 505 yards and still lost.

Tom Brady had one of the greatest statistical performances in Super Bowl history and came up short.

Foles was Super Bowl MVP, the first backup to win it since Brady himself in 2001. What St. Louis and Kansas City had classified as a fluke, Philadelphia reframed as legacy.

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Joe Flacco

Joe Flacco was watching NFL games on his couch in October 2023. Not rehabbing. Not training quietly.

Unemployed, 38 years old, released by the Jets in August, wondering, probably, whether the phone was going to ring again.

Cleveland called in mid-November, not to start, not to compete, but to sign him to the practice squad as emergency depth after Deshaun Watson’s shoulder gave out and P.J. Walker struggled as the replacement. The transaction barely registered a headline.

Then Walker faltered again. Flacco was elevated, activated, and thrust into a start against the Rams in Week 13, and proceeded to produce one of the most remarkable five-game stretches any quarterback has delivered, let alone a 38-year-old whose best days were thought to be behind him: 1,616 yards, 13 touchdowns, a 90.2 passer rating, four consecutive 300-yard games, and a wild card berth for a franchise that had been spiraling.

He became the first player in NFL history to throw for 250-plus yards and two-plus touchdowns in each of his first five appearances with a team.

The Browns went 4-1. AP Comeback Player of the Year, weeks after unemployment. Couch. Practice squad. Canton conversation.

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