If we look at objective measures designed to get to the heart of what a quarterback is contributing to a team, Case Keenum is playing at a higher level so far in 2017 than any Vikings quarterback has played over a full season since Brett Favre in 2009.
Yes, Keenum has been better than Sam Bradford was for the duration of 2016. Yes, he's been better than Teddy Bridgewater was in 2015 or 2014. He's certainly delivered better than any QB play the Vikings received from 2010 through 2013.
Before you dismiss this as nothing but a ridiculous hot take, let me explain:
There are no perfect metrics when evaluating the play of a quarterback in a vacuum, but three that aim to do a pretty good job are Total QBR (developed by ESPN) as well as defense-adjusted yards above replacement (DYAR) and defense-adjusted value over average (DVOA), both used by Football Outsiders.
Total QBR, developed in 2011, "incorporates all of a quarterback's contributions to winning, including how he impacts the game on passes, rushes, turnovers and penalties" while also seeking to contextualize success or failure depending on game situations. DYAR and DVOA attempt to do similar things, with different formulas.
Keenum so far this season ranks No. 6 in Total QBR among NFL QBs. He's No. 5 in DYAR and No. 4 in DVOA. There are only three QBs in the NFL who are in the top six in all three categories: Tom Brady, DeShaun Watson and Keenum.
Bradford in 2016 — despite the consensus being that he played well and despite him setting an NFL record for completion percentage — finished No. 17 in ESPN's Total QBR standings, No. 16 in DYAR and No. 17 in DVOA. That's decidedly average.
Bridgewater in 2015 finished No. 17 in Total QBR, No. 21 in DYAR and No. 22 in DVOA among NFL quarterbacks. Bridgewater ranked even lower in all three categories as a rookie in 2014.
No qualified Vikings passer finished higher than No. 16 in any of those three categories in any season between 2010 and 2013, and many finished much, much worse. You have to go back to 2009, when Favre was top-five in all three categories, to find a comparable Vikings quarterback performance.
That said, this is not an argument that Keenum is better than Bridgewater or Bradford — only that his production and play for the first half of 2017 was better than what either of those QBs have produced as starters over full seasons with the Vikings.
It's also important to acknowledge that Keenum has had benefits this year that those two QBs did not have in past years. The Vikings' offensive line play this season has been light years ahead of the mess Bradford endured in 2016 and has been a considerable upgrade over what Bridgewater experienced in 2015.
Keenum, too, has faced some suspect defenses and has only had a 6½-game sample size, whereas Bridgewater (16) and Bradford (15) had much larger samples the past two years. These things can even out over time.
What we don't know is how this year would have played out with a healthy Bridgewater or Bradford playing the first eight games.
Any decision the Vikings might make about whether to turn to Bridgewater or Bradford — if and when either is fully healthy and ready to play — hinges on answering this question: Could either (or both) do more with this offense than Keenum is doing right now?