If you trust the math, there is a way for the Vikings to afford Kirk Cousins

The Vikings remained publicly agnostic about their quarterbacking options last week at the NFL combine; coach Mike Zimmer laid out the strengths and weaknesses of all his in-house candidates, while General Manager Rick Spielman batted away a report that the Vikings had decided not to use the franchise tag on Case Keenum and said the team had not made a decision on any of its options.

In fact, Keenum was not tagged by the deadline and joins Teddy Bridgewater and Sam Bradford as free agents. There is every indication the Vikings are marshaling resources for a competitive and lucrative run at Washington quarterback Kirk Cousins, all while assessing their salary cap situation amid the flurry of rumors that could serve to drive up the price of free-agent quarterbacks.

How far will the Vikings go, and at what cost, with core players — defensive end Danielle Hunter, linebackers Eric Kendricks and Anthony Barr, as well as wide receiver Stefon Diggs — all set to become free agents after 2018?

Zimmer cautioned at the combine that a quarterback move shouldn't come at the expense of the rest of the roster, and deals affecting the defense make up an outsized portion of the Vikings' potential contract extensions in the next year.

But the good news for Zimmer is, the Vikings might be able to do it all.

The team's decision not to offer a restricted free-agent tender to versatile backup offensive lineman Jeremiah Sirles, whom they'd like to retain, was driven at least in part by the fact that the lowest RFA tender this year is $1.9 million, which would only guarantee the Vikings the right to match any offers while stripping away their ability to design a contract with a cap figure to their liking.

Why does that matter?

When you're trying to squirrel away money for a pricey QB contract, every dollar is important, and while the Vikings weren't sending quite the same signals they did last year — when they effectively told free agents they'd get back to them after solving their offensive line issues first — there's little doubt their quarterback situation tops their March to-do list.

After talking to a number of NFL sources at the combine, I thought we'd go through a little exercise, to take an educated guess at how the Vikings might be able to get a deal done with Cousins, retain a number of their own free agents and leave themselves enough money for other deals this year and extensions in the future.

A $177.2 million salary cap for 2018, coupled with the Vikings' $13.4 million of leftover space from 2017, gives them an adjusted salary cap of $190.6 million for 2018. If the salary cap continues to rise at a rate of around $11 million-$12 million a year, as it has in recent seasons, it would be around $190 million in 2019 and between $200 million and $202 million in 2020 (before team-specific adjustments).

Cousins is reportedly seeking a three-year, fully guaranteed deal in the neighborhood of $90 million, though it remains to be seen what he'll actually receive and whether the Vikings would be willing to go that high. For now, we'll assume a three-year guaranteed deal for $84 million, which would help him surpass Jimmy Garoppolo's average annual salary of $27.5 million (albeit with a shorter deal).

The Vikings would need to give Cousins plenty of cash up front, likely through a modest signing bonus and a roster bonus that puts a large chunk of the cap hit in Year 1 of the deal. It inherently means the Vikings would eclipse the 10 percent cap space threshold in 2018, since Cousins would likely carry a cap figure well north of $30 million in the first year.

We'll give Cousins a $9 million signing bonus, as well as a $32 million roster bonus and $2 million base salary in Year 1. That puts plenty of cash in his pocket early (though roster bonuses of that magnitude are often paid out in a couple of installments), and takes a $37.25 million bite out of the salary cap in Year 1 (counting an annual $250,000 workout bonus). In Years 2 and 3, though, when the Vikings need cap space for Diggs, Hunter, Kendricks and Barr, they'd have only $46.75 million in cap space left to devote to Cousins.

In 2019 and 2020, we'll give Cousins fully guaranteed base salaries of $20 million and $20.25 million, respectively, as well as his workout bonus. Counting his signing bonus prorations, he's got cap numbers of $23.25 million and $23.5 million in Years 2 and 3.

Assuming a $37.25 million cap number in 2018 for Cousins, the Vikings still have $11.64 million in available cap space, and they could recoup a few million by restructuring deals for veterans Brian Robison, Jarius Wright and Latavius Murray. They'd need a backup quarterback, possibly another tackle if they move Mike Remmers to guard, some cash for modest deals on their in-house free agents and money for draft picks.

But with the Cousins deal that was just outlined and moves that recoup, say, another $6 million in cap space, the Vikings would still have $17.64 million to spare for 2018. And by the time they need to pay some of their other young players, Cousins' cap figure, as a percentage of the Vikings' overall spending, would be roughly in line with what other teams spend on their passers. They would have nearly $50 million left for 2019, and $91 million for 2020 (with plenty of players to be signed between now and then, of course).

We're a long way from all of this being finalized; the Vikings would have to decide how far they're willing to go for a quarterback who's gone 26-30-1 in the regular season and 0-1 in the playoffs.

But if the Vikings deem Cousins worthy of a lavish contract, there are ways for them to pay him and retain enough cash for their other needs. It would require a big bite out of their 2018 cap, but by the time the Vikings' other draft picks come to the table, there would be money left for them, too.

Ben Goessling is a Vikings beat reporter for the Star Tribune. @GoesslingStrib E-mail: ben.goessling@startribune.com