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Imagine a world where everything is the same except for two facts have been changed.

OK, this thought exercise could be a lot more interesting if we didn't narrow the focus to the Vikings and their search for a quarterback in 2018, but that's what I'm going with here.

In this slightly tweaked reality, Teddy Bridgewater has still not played a meaningful down in two seasons. Sam Bradford still played just six quarters last season and has a knee condition head coach Mike Zimmer calls "degenerative."

But in this reality, Case Keenum's 2017 performance for the Vikings has been wiped off the record books, as has Kirk Cousins' 2017 season with Washington.

We're living in a world where Cousins had the third-best QB rating in Pro Football Focus' metrics in 2016 and sixth-best in 2015 — better than a healthy Bradford (ninth in 2016) and a healthy Teddy (12th in 2015) — while ignoring the dip he took down to 17th in 2017.

We're firmly entrenched in the narrative that Keenum is no more than a decent backup QB who was No. 31 in that same PFF stat in 2016. We've discarded his one shining moment — 2017 — when he outperformed Cousins in many ways.

How much simpler, in this world, would the Vikings' offseason QB pursuit be?

A lot, right?

Concerns about the recovery of Bridgewater and the long-term health of Bradford are serious impediments to a team with Super Bowl aspirations. The Vikings seemingly are not in a position to waste any time — even if it's just a year — trying to figure out where those players stand long-term.

Keenum, though, poses a more interesting question (we're back to actual reality for a moment, by the way). He was plenty durable in 2017 and doesn't have long-term injury questions. The only question, as Mike Zimmer mused aloud last week at the NFL Combine, is whether Keenum's strong 2017 season for the 13-3 Vikings was a trend or a mirage.

If Keenum had performed merely adequately last season — and let's face it, the Vikings seemed to have questions about his level of play even midway through the year, when signs pointed to Bridgewater taking over at some point — this QB conundrum has a clearer focus.

If we erase 2017 altogether, it becomes crystal clear. Then we're talking about a journeyman and two injury risks vs. a guy ascending into the discussion as easily one of the eight to 10 best QBs in the league in Cousins. No matter the cost — and Cousins figures to easily be the most expensive of the bunch, though the Vikings can afford him — he would definitely be worth it.

But of course 2017 happened. Cousins was hardly terrible — and his supporting cast was diminished from what it was in previous years — but it was enough to raise more doubts about his place in the QB hierarchy. Meanwhile, Keenum performed at a level few could have foreseen.

From 2012-14, as a backup and spot starter behind Robert Griffin III, Cousins had 18 TDs, 19 INTs and a 77.5 passer rating.

From 2013-16, as a backup and spot starter, Keenum had 24 TDs, 20 INTs and a 78.4 passer rating.

Cousins, a former fourth-round pick, took his opportunity in 2015 and ran with it, putting together two very strong seasons and a decent one.

Keenum, a former undrafted free agent, only has one strong season to his credit.

Is he on the verge of being consistently good, as Cousins proved to be, or is he due for a major regression?

That's the expensive question staring the Vikings in the face — one that was complicated very much by what happened last year.