The key to a happy, harmonious team, fan base, front office and coaching staff usually rests on the ability of their offensive line to consistently dominate the other team's big fellas.

Before we knighted Sean McVay for reinventing the game of football last season, the Rams rebuilt the young man's offensive line into one of the top two or three units in the league. The Rams are a league-best 11-1, winning 54-51 shootouts, averaging 9.1 yards per pass and 4.8 per run.

Yes, Sean's 32-year-old offensive mind could prove to be historically sharp. But that kind of balance can't be found — by any play-caller — behind a line that lacks continuity or top-line talent and strength.

In Kansas City, where the Chiefs are an AFC-best 10-2, Andy Reid's brilliant, rejuvenated mind has skill players going every which way in a symphony of three-way misdirection. Patrick Mahomes reads the defense's confusion and flicks the ball left or right, back or forth, short or long.

Try doing all that fancy, futuristic movement with defenders crashing through the front door at the snap of the ball. It wouldn't work.

In Minnesota, an ongoing story line features old-school head coach Mike Zimmer vs. new-school offensive coordinator John DeFilippo. Zimmer is open about wanting more commitment to the run. DeFilippo accepts the boss' evaluation as having some merit but also expresses his opinion that bosses aren't always right.

"Balance to me is going to be different each week," DeFilippo said. "If you just go in with the same plan to attack an opponent each week, I don't think that's going to give you the best chance for success."

Their problem isn't communication. It's not the age of the school of football they attend. It's the fact their offensive line hasn't played well enough to satisfy either one's approach consistently. And that makes offensive line the team's No. 1 priority heading into the offseason.

Meanwhile, the situation up front in Seattle sits at the other end of the spectrum. Pete Carroll wants to run the ball, and, by gosh, run the ball they have.

It started with Carroll firing offensive coordinator Darrell Bevell and Tom Cable, his line coach and run game coordinator, after Seattle missed the playoffs last season.

"We needed to do some things a little differently," said Carroll, whose team plays host to the Vikings on Monday night. "Take advantage of the personnel we had and the style of offensive linemen we were able to get."

In doing so, the hope, Carroll said, was to elevate quarterback Russell Wilson's "awareness of what's going on in the game."

Carroll hired fellow run-game enthusiasts Brian Schottenheimer and Mike Solari as offensive coordinator and line coach, respectively. Solari then talked massive right guard D.J. Fluker into following him from the Giants to Seattle.

"I'm really grateful that it's worked out," Carroll said. "Russell is more in command than he ever has been."

Wilson is on pace for a career low in interceptions and career highs in passer rating and touchdowns. And no other team in the league averages more runs per game (31.7) than Seattle.

Of course, there was that two-game hiccup to start the season. Seattle started 0-2 with 12 sacks allowed. They had thrown the ball 69 times and run it 38.

As an organization, Seattle recommitted to the run. Since then, the Seahawks have run the ball 326 times and passed it 257 while averaging 164.8 rushing yards per game, going 7-3 and climbing to the NFC's fifth playoff spot.

Of course, it helps that Fluker returned from a hamstring injury in Week 2. He won't play Monday because of that hamstring, but undrafted rookie Jordan Simmons stepped in for him against the Rams in Week 10 and played well.

It also helps that guard J.R. Sweezy returned from Tampa Bay this season and has started all 12 games. That right tackle Duane Brown has proved he was worth trading for last year. That center Justin Britt has been durable. That right tackle Germain Ifedi was a first-round pick in 2016.

"Things have fit well," Carroll said. "Those guys up front have done a good job kind of setting the tone for how we play our football."

And therein lies the key to NFL happiness or the lack thereof.

Mark Craig is an NFL and Vikings Insider. Twitter: @markcraigNFL. E-mail: mcraig@startribune.com