Rather, it comes from the data-inclined Five Thirty Eight.
The numbers say Peyton Manning wasn’t just mediocre this year. They say he wasn’t just bad relative to his past performance. They say he wasn’t even just flat-out bad. They say he was historically bad when it comes to a Super Bowl QB:
Let’s compare Manning’s overall season to those of other Super Bowl starting QBs over the years. If we judge by (adjusted net yards per attempt) ANY/A compared to the league average from the season in question, Manning’s 2015 ranks second-worst, again ahead of only Vince Ferragamo’s catastrophic 1979 numbers. And Ferragamo’s damage was at least limited: He started only five of the Rams’ 16 games, and played in an age when teams passed less, so a poor QB wasn’t as harmful to his team’s chances as today. (Not that it mattered for Ferragamo; his Rams lost the Super Bowl to the Steelers 31-19.)
Manning, by contrast, plays in a pass-crazed era and threw the ball about as often per game as his peers, despite his horrible passing efficiency rates. The result, according to Football Perspective founder Chase Stuart’s method of judging QB value versus league average (which considers both passing and rushing value) was by far the worst regular season by a Super Bowl starter since the merger.
Also of interest, as the post goes on to note: it might not matter because historically teams with poor QB play in the Super Bowl compensate in other areas.
Regardless, it’s interesting to think of an all-time great as the worst ever. Give the entire post a read if you have a few minutes.