NFL franchises have become billion-dollar operations employing 60 or more athletes, a dozen or more coaches, platoons of support staffers and layers of front office bureaucrats. The Vikings probably have more people working in their PR department today than Bud Grant had on his coaching staff when he was taking teams to Super Bowls.

No matter how many people become involved, winning NFL franchises are usually defined by their uncommon common denominators: their head coach and their starting quarterback.

Here’s what’s tricky about finding the right guy at each position: No two look exactly alike. NFL GMs can’t stereotype, or profile. They have to be able to recognize unique talent in unfamiliar packaging.

The final four coaches are Bill Belichick, Chuck Pagano, Mike McCarthy and Pete Carroll.

Belichick is a dour former defensive coordinator who got fired in Cleveland. Pagano is an enthusiastic former defensive coordinator. The Packers hired McCarthy when he was the offensive coordinator for one of the worst offenses in the league. Carroll had been fired by two NFL teams before going back to college.

Carroll is a player-friendly cheerleader. Belichick is Darth Vader in a sheared hoodie. Pagano and McCarthy are unremarkable personalities who would tend toward anonymity if their teams didn’t win.

The Final Four quarterbacks are Tom Brady, Andrew Luck, Aaron Rodgers and Russell Wilson. What they have in common are differences.

Brady is one of the great pocket passers in league history, a sixth-round draft pick who turned into a prototype. Luck was the first pick in the draft.

Rodgers slipped to the 24th pick in the draft, sat for three years and became the new prototype. Russell Wilson, the most successful of the new-breed mobile quarterbacks, lasted until the third round, yet won the starting job as a rookie in training camp.

All four finished in the NFL’s top 10 in passer rating. Wilson ranked 10th, but increased his value by easily leading the NFL in rushing yards (849) and rushing touchdowns (six) by a quarterback. He would have led the Vikings in rushing by almost 300 yards.

If you’re an NFL general manager or scout, what do you take from this?

That quarterbacks who don’t have to start right away, like Brady and Rodgers, benefit from the time on the sideline? Then how do you explain Luck being the most prolific young passer in NFL history, and Wilson winning a Super Bowl in his second season?

That pure pocket passers like Peyton Manning and Brady are the best bet for success? That would discount Luck’s remarkable athletic ability, Rodgers’ athletic creativity and Wilson’s gift for scrambling and gaining massive yardage on the ground without taking big hits.

If there is a common denominator among great coaches and quarterbacks, it is one that can’t be found at the NFL combine or in measurable athletic ability. It is “it.”

“It” is the ability to make the right decision under extreme duress. “It” is the ability to adapt to surprising developments within a game.

Coaches have to make game-deciding decisions with a clock running. Quarterbacks are given split seconds to decipher defenses, choose receivers and deliver passes into small, moving windows while large men try to do them harm.

A lot of intelligent football coaches have devised a lot of ingenious game plans that have failed. A lot of superior athletes have found their brains and reflexes wanting when facing live NFL defenses.

Last winter, the Vikings hired an older defensive coordinator who had been passed over so many times for NFL head coaching jobs that he considered abandoning the search. Last spring, the Vikings drafted a quarterback with the 32nd pick in the first round.

Every other NFL team had the opportunity to hire Mike Zimmer or draft Teddy Bridgewater, just as most NFL teams had the chance to hire McCarthy or Belichick, or to draft Brady, Wilson or Rodgers.

As Vikings fans watch the championship games today, they will see four quarterbacks and perhaps four coaches with the ability to think on their feet. And Vikings fans can take solace, knowing that their coach and their quarterback, in their first year together, both hinted at having “It.’’