While such instances are rare, Mahomes isn't the first recipient of a contract spanning 10-plus years. Here's how the other decade-long deals panned out:
March 2001: Brett Favre gets 10 years, $100M from Packers
Favre didn't anticipate playing beyond 2006 but took a 10-year deal at 31 to help Green Bay massage the salary cap. Though his best days were behind him, Favre still led the NFL in passing touchdowns once and gave the Packers four Pro Bowl seasons after signing the deal. The club made the playoffs five times over the next seven years, and Favre broke the NFL career passing touchdowns record in a Packers uniform.
Favre didn't finish the contract in Green Bay, though, as he was traded to the New York Jets in 2008 after ending a brief retirement. The Jets released him in 2009 after he retired again, and he signed a fresh contract when he made a second comeback as a member of the Minnesota Vikings.
March 2001: Drew Bledsoe gets 10 years, $103M from Patriots
Bledsoe was already regarded as the greatest quarterback in Patriots history by the time he signed his deal. And at 29, it appeared he was signing up to spend the rest of his career in New England. But Bledsoe played only two more games for the Patriots, as an injury in Week 2 of the 2001 season spelled the beginning of the Tom Brady era.
Bledsoe helped the Patriots reach the Super Bowl that year after relieving an injured Brady in the AFC Championship Game and collected a ring as Brady's backup. Bill Belichick and Co. traded him to the Buffalo Bills that offseason with nine years left on his contract. While Bledsoe got off to a hot start with his new team, he fizzled the following season and was released after the 2004 campaign.
September 2002: Donovan McNabb gets 12 years, $115M from Eagles
McNabb owns the record for the longest contract in NFL history. At 26, he agreed to a 12-year pact with Philadelphia. The deal quickly paid dividends, as McNabb led the Eagles to a Super Bowl berth two years after signing. The Eagles were perennial contenders with McNabb, though they never hoisted the Lombardi Trophy or returned to the Big Game after the 2004 season.
Shockingly, the Eagles traded him to the Washington Redskins in 2010 with four years remaining on his contract. Though only 34, McNabb's game fell off quickly in Washington, which made the five-year extension he received midway through the 2010 campaign a head-scratcher. He was relegated to third-string duties late in the season and was traded to the Vikings in July 2011. McNabb spent less than one miserable season in Minnesota before he was released, and he retired soon after.
May 2003: Daunte Culpepper gets 10 years, $102M from Vikings
One of the most exciting young quarterbacks in football at the time, Culpepper was 26 when he inked his extension. He immediately rewarded the Vikings with two of his best seasons. In 2004, Culpepper established a new NFL record for total yards by a quarterback, racking up 5,123. He led the league in passing that year with over 4,700 yards.
But he got off to a horrid start in 2005, and in late October, he tore his ACL, MCL, and PCL. The Vikings shipped him to the Miami Dolphins, who were more encouraged by his injury outlook than that of Drew Brees. Culpepper struggled with the Dolphins and was released after one year, with six seasons remaining on his contract. The three-time Pro Bowler had forgettable stints with the Oakland Raiders and Detroit Lions before exiting the NFL for good.
December 2004: Michael Vick gets 10 years, $130M from Falcons
Atlanta gave a 24-year-old Vick, perhaps the most electrifying quarterback the NFL had ever seen, the richest contract in league history. Vick steered the Falcons to the NFC divisional round that year and appeared to be ascending, but he plateaued. While he became the first quarterback to rush for 1,000 yards in a season in 2006, his lack of progress as a passer kept him from joining the top echelon of quarterbacks and the Falcons from becoming a Super Bowl threat.
Everything came crashing down in the summer of 2007, as Vick was arrested for his role in a dogfighting ring and spent most of the next two years in prison. The Falcons recovered nearly $20 million in arbitration, and the signal-caller signed with the Eagles upon returning to professional football.