The Broncos spent $36 million for the worst version of Case Keenum to date

Keenum’s breakout 2017 is proving unsustainable, but there’s still time for a turnaround.

On Monday night, the Broncos’ spot atop the AFC West was in Case Keenum’s hands. The free agent acquisition trailed the Kansas City Chiefs 27-23 with only 22 seconds left. But Denver had the ball at the KC 28, and four-time Pro Bowler Demaryius Thomas had just broken free down the right sideline. An on-target delivery looked like a surefire touchdown.

What Keenum gave the Broncos was not an on-target delivery.

It’s not often one play can sum up a player’s month, but that pretty much does it. When Keenum takes the field next week for a showdown against the Jets, it will have been 27 days since his last touchdown pass. He has missed zero games and zero snaps in that span. That’s not what Denver had in mind when they handed him $18 million per year to be the latest short-term solution to an unstable carousel of quarterbacks — but the Broncos knew exactly what they were getting into when they signed Keenum last spring.

Case Keenum is off to a bad start, even by pre-2017 Case Keenum standards

If Keenum’s 2018 was based on his 2017 season alone, his two-year, $36 million contract would be considered one of the league’s biggest bargains. His underwhelming start would be considered a surprising slump.

Last year, Keenum was a top 10 quarterback who recorded a 98.3 passer rating (higher than Aaron Rodgers) and led three comeback victories as his Vikings went 12-3 in games where he was the team’s primary passer. He even had a 318-yard performance in the Divisional playoff to help push Minnesota to the NFC Championship Game.

That year was a major breakout, and while the Broncos knew a regression was on the horizon, the team made a calculated risk on a young veteran who, at the very least, produced several hot starts in his past. But through four games, Keenum’s trajectory has crashed past last year’s stellar season, through his career baseline of “acceptable spot starter,” and into the “immediately replaceable” tier of 2017’s starting quarterbacks.

Here’s how he’s looked over his first four starts each season he’s started at least four games:

Keenum currently ranks 31st among 34 qualified starting quarterbacks with a 72.1 passer rating. One of the players he’s outpacing is Bills rookie Josh Allen. The other two are Tyrod Taylor and Sam Bradford; players who’ve already been replaced by rookie quarterbacks in 2018.

Swapping out Keenum is not a great option for the Broncos in 2018, but it might be a necessity if he can’t shake off an awful start.

Where does Case Keenum stack up next to Denver’s other underwhelming quarterbacks?

The Broncos won a Super Bowl after the 2015 season, but the team hasn’t had an above-average quarterback since 2014 when Peyton Manning whipped 39 touchdown passes in his penultimate season before resigning to a life of Nationwide commercials. The performances since then have been...unfortunate.

The good news is Keenum has been better than a diminished Manning. The bad news is, statistically, he’s been worse than any of the passers Denver had on its roster in 2017 — and those were the guys over whom he was supposed to provide a clear, $36 million upgrade.

Typically, this kind of start would open questions about Keenum’s hold on a job where no quarterback has started a full 16-game season since ‘14, but the Broncos don’t have many options who can press the free agent signee for playing time. 2016 first round pick Paxton Lynch didn’t make it to a third season with a team and is so highly regarded around the NFL that he’s currently a free agent, Denver’s backup quarterback situation involves a vastly-improved Mr. Irrelevant (Chad Kelly) and a former fifth-round pick so underwhelming he could only crack the Browns starting lineup for a single game between 2016 and 2017 (Kevin Hogan).

Broncos fans are making the case for Kelly, who impressed in the preseason, but he’s still an extremely raw prospect. For the foreseeable future, it’s Keenum in Colorado, for better or for worse. But things aren’t as bad as his one-month trial suggests.

Struggles aside, Keenum has been a useful fourth quarter QB who’s due for improvement

Keenum’s history suggests he’ll bounce back — probably not to his 2017 peak, but he’ll be closer to a league-average quarterback than one of the game’s statistical worst. His 4.3 percent interception rate is nearly double the 2.1 percent rate he’d posted over his previous six seasons. And while there have been some absolute clunkers in his six picks this fall, that number is likely to decline moving forward. His touchdown rate, on the other hand, is likely to rise after languishing at a career-low 2.1 percent through four games.

But the biggest trait working in Keenum’s favor has been his ability to punch back when facing fourth quarter deficits. When the Seahawks took a 24-20 lead with 14:46 to play in Week 1, he threw for 61 yards on the ensuing drive to hit Thomas with what proved to be a game-winning touchdown. In Week 2, he led four straight second-half scoring drives to lead the Broncos from a 12-0 deficit to a 20-19 win over the Raiders.

Even on Monday, before he overthrew Thomas down the sideline, he’d completed four straight passes to lead Denver from its own 15 to the Kansas City 28-yard line.

But then he missed that game-winning third down throw. And one week earlier, he led the Broncos to zero points in quarters two through four against the Ravens. The cons still outweigh the pros on Keenum’s 2018 resume.

There’s still time for that to change, and while his career suggests he won’t be as good as he was in ‘17, those numbers also say he won’t be as bad as he’s been to kick off his follow-up season. That may not be enough. The Broncos have won with bad-to-average quarterbacks before, but that was with a dominant defense to control opponents. This year’s Denver squad ranks just 19th in yards allowed per play and 17th in third-down defense. They’re going to need 2017 Keenum to overcome those mediocre numbers — not career-average Keenum.

That’s a problem for the Broncos. The question now is whether quarterbacks coach Mike Sullivan can find a way to harness the gushing vein of above-average QB play the Vikings mined last fall when they tapped Keenum as their starter.