The biggest 'fluke' seasons for NFL QBs

Booger: Dak is the most disrespected QB in the NFL (1:14)

Booger McFarland would take Dak Prescott over Carson Wentz, as McFarland says Prescott has not gotten "his just due" based on his accomplishments. (1:14)

There's a three-headed quarterback battle going on in Washington, but right now journeyman veteran Case Keenum appears to be in the lead. This offseason, the Redskins sent a sixth-round pick to Denver in exchange for Keenum. That's a pretty low price, considering that Keenum was one of the best quarterbacks in the league just two years ago. The Redskins are hoping Keenum can duplicate his 2017 performance, when he led Minnesota to the playoffs. But that season stands out on Keenum's record as far superior to the rest of his career. It looks like a fluke.

Plenty of players have put up fluke seasons. But it's the quarterback flukes that stand out the most. Some of these players have bounced around from team to team, trying to recapture the magic of one great early season. Others come out of nowhere to have one huge season late in their career. If your team can't get a franchise quarterback, the next-best thing is to luck into lightning in a bottle by getting a veteran on the cheap and having him put up a big fluke year.

We've put together a list of the biggest fluke seasons by quarterbacks in Football Outsiders' play-by-play database, which goes back to 1986. This wasn't as simple as just taking the biggest difference between a quarterback's best year and his other years. We also considered how long each quarterback played as a starter and as a backup. For example, the player with the biggest difference between his best year and his second-best year, in both advanced stats (Football Outsiders' DYAR, or defense-adjusted yards above replacement) and standard stats (passing yards)? Patrick Mahomes, of course. But that's only two seasons, and in one of them Mahomes had just one start! Mahomes has plenty of time to prove he's not a young one-year wonder like Robert Griffin.

However, we start our biggest fluke year list with another current young star. Like Mahomes, he excelled in his first season as a starter. But he's fallen off that pace in the two years since.

10. Dak Prescott (2016 Dallas Cowboys)

On the surface, Prescott's three NFL seasons might not look that different from one another, but that's partly because an increase in attempts has kept his total stats somewhat stable. By advanced metrics, however, Prescott's second and third seasons have fallen far short of his rookie performance.

Prescott was fourth in the league in total value as a rookie (as judged by DYAR). In the two years since, he's fallen to 17th and then 25th. His QBR has fallen similarly, from 77.6 as a rookie to 69.9 and then 55.2 last year. Prescott is only 10th on this list because he's just three years into his career. He certainly could have another highly efficient season that rivals his rookie year. But so far, that first season sticks out as a clear exception on his statistical record.