Paul Sancya/Associated Press

The Seahawks should have stunk this year.

OK, maybe "stunk" is too strong a word; no team coached by Pete Carroll and quarterbacked by Russell Wilson can ever be all that terrible. But the Seahawks should have been like the Broncos this season: drearily mired in mediocrity with one foot in the past and no real plan for the future.

They broke all the rules of forward-thinking, 21st-century NFL roster management and on-field strategy this year. It made them a source of derision among analytics types (like me) and should have knocked them out of the playoff chase.

Instead, they are 9-6, locked into a wild-card spot and a trendy pick to pull off at least one postseason upset.

Carroll just signed a multiyear extension, and Wilson has quietly had the best season of his career. The Seahawks have turned the page on the Legion of Boom era without massive organizational upheaval or cataclysmic roster demolition.

According to modern wisdom, none of this should have happened. None of what the Seahawks did this year should have worked.

But by breaking all of the following rules at the same time, the Seahawks proved that modern wisdom can still learn a thing or two from the old-school football mentality.

Broken rule No. 1: They sacrificed talent for culture

It shouldn't have worked because letting the likes of Richard Sherman, Michael Bennett and Jimmy Graham depart in favor of what veteran linebacker Bobby Wagner called "hungry" players with "something to prove" is a fine way to build a roster full of guys who look like they are trying extra hard when chasing down an opponent who's running for his third touchdown of the game.

Elaine Thompson/Associated Press

Sports teams just don't get better by getting less talented, no matter how much nicer the new guys are to work with.

It worked because the Seahawks traded ability for reliability.

Jettisoning Sherman and Bennett (and losing Kam Chancellor to a career-threatening neck ailment and Earl Thomas to a broken leg) weakened the Seahawks defense considerably this season. After ranking in the top five in Football Outsiders' defensive DVOA from 2012 to 2016, they dropped to 13th last season and 16th this year. Conventional stats tell the same story: They rank 20th in yards allowed entering Week 17, having ranked 11th last year and in the top five for the five previous years.

But this year's Seahawks are less susceptible to mood swings than the 2015-17 teams. Football Outsiders uses "variance" to measure how volatile a team's performance is each week. The Seahawks rank sixth in that category this year, making them one of the most stable week-to-week teams in the league. They were 13th last year and 29th during the sturm und drang of 2016.

The 2016 and 2017 Seahawks descended into drama late in the year, and the mercurial Sherman was often in the thick of it. This year's Seahawks have actually coalesced in the second half of the season.

So there may be something to this whole "chemistry" business, especially when a few of the ingredients have a habit of blowing up the test tube.

Broken rule No. 2: They cared about establishing the run

It shouldn't have worked because "establish the run" is 1970s high school football coach reasoning that lives on in the NFL only thanks to old-fashioned, comically ineffectual Jeff Fisher types.

Seahawks offensive coordinator Brian Schottenheimer is a former Fisher assistant who vowed to run the ball when opponents were expecting it in the offseason. In the high-scoring, pass-happy NFL, establishing the run is a great way to spot opponents a 14-0 lead while demonstrating your manliness by running off-tackle for two yards at a time.

Paul Sancya/Associated Press

It worked because the run-first approach allows the Seahawks, who rank just 18th in the NFL in net yards, to do several things efficiently:

• Avoid turnovers. The Seahawks have surrendered just 10 giveaways, the lowest total in the NFL. Fewer passes mean both fewer interceptions and fewer chances for strip-sacks, which constitute a high percentage of NFL fumbles.

• Enhance play action. Per Football Outsiders, the Seahawks use play action on 31 percent of their pass plays (more than any team but the Rams) and average 9.0 yards per play-action pass (fifth in the NFL).

• Play better situational football. The Seahawks rank eighth in the NFL in red-zone efficiency, per Football Outsiders. They have also been one of the league's most effective short-yardage teams: They are 5-of-5 when rushing for 4th-and-1 conversions, for example, according to NFL GSIS.

The Seahawks go three-and-out more than most teams (26.5 percent of drives, 29th), a sign that establishing the run too often means establishing the punt. But eliminating turnovers and punching in more touchdowns have made the trade-off worth it.

The run-first approach, like the defensive personality adjustment, has stabilized the Seahawks. Wilson ran an NFL Blitz video game offense behind a nonexistent O-line for the last three years, alternating between CGI superhero highlights and getting sacked out of field-goal range in crucial situations. This year's Seahawks are far less exciting but also far less self-destructive.

Broken rule No. 3: They drafted running backs and punters

It shouldn't work because modern draft logic tells us that running backs are so interchangeable that teams should never draft them in early rounds, sign them to big contracts or do anything but bake batches of them out of Rice Krispies squares and fondant.

So the Seahawks made a big mistake by drafting Rashaad Penny in the first round. And selecting punter Michael Dickson in the fifth round was just an outrage.

It worked because…OK, actually, it didn't. Dickson has been excellent, and fifth-round pick Tre Flowers has proved a capable starter in the secondary, but Penny ranks third on the team in rushing, and the rest of the draft class has not done much yet.

But the overall Seahawks player-acquisition plan has worked. The team has developed late-round picks from past drafts (running back Chris Carson, receiver David Moore) and undrafted rookies (defensive lineman Poona Ford). Seattle acquired useful, affordable free agents (safety Bradley McDougald, guard D.J. Fluker, kicker Sebastian Janikowski) and found roles for draft-bust reclamation projects (defensive end Dion Jordan, linebacker Barkevious Mingo).

Otto Greule Jr/Getty Images

The Seahawks' roster-management model this season looks a little like the vintage Patriots model: the draft was just a multi-pronged search for talent. It wasn't sexy, but it made the Seahawks younger, cheaper and (yes) a little hungrier without gutting the roster.

Broken rule No. 4: They rebuilt on the fly

It shouldn't work because everyone knows that the Browns' Moneyball model is the only way to rebuild a roster these days: be dreadful on purpose for two to 27 years, get everyone fired, hoard draft picks and cap space like your weird neighbor hoards canned goods in his backyard bunker and then get congratulated for almost reaching the playoffs some day in the far-flung future.

It worked because any team with a franchise-caliber quarterback like Wilson can rebuild on the fly. Here's what it takes:

• Some painful, unpopular decisions involving veterans: See the Sherman-Bennett-Graham moves.

• Creative player-acquisition tactics: See signings like Jordan, Mingo and Jaron Brown, plus last year's Duane Brown trade.

Tony Avelar/Associated Press

• Shrewd long-range planning: Wilson's 2015 contract was designed to avoid cap headaches. The Seahawks began developing Legion of Boom replacements in 2017. Duane Brown and Tyler Lockett signed offseason extensions that will prevent future cap problems.

• Sound coaching: Carroll has done another masterful job. Schottenheimer will never be mistaken for Sean McVay, but the staff is an upgrade over what the Seahawks had before, and everyone is on the same page.

The Seahawks also didn't get carried away by some philosophically pure Moneyball model of rebuilding. They signed the 40-year-old Janikowski to kick, gave Brandon Marshall a tryout at wide receiver and kept Thomas around against his will in the hope of providing some leadership/continuity.

None of these moves helped much, but they did signal an urgency to remain competitive and rebuild quickly. The team responded by proving to be a tough out early in the year and by defeating the Packers, Panthers, Vikings and Chiefs—teams that look a little like the old Seahawks at times, with their brilliant but erratic personalities—down the stretch.

Now the Seahawks are a playoff team with a franchise quarterback, a developing core and just over $60 million in 2019 cap space. They'll be Super Bowl contenders again in a hurry, if they aren't already.

What the Seahawks did may not be the best way to build a playoff team. But they proved it can work, especially when the rest of the NFL is either trying to win by throwing a million passes or rebuild by assembling a hundred future draft picks, leaving plenty of space for a franchise that does things differently.

So the next time you see a team like the Seahawks doing and saying all the wrong things in the offseason, take a closer look. Maybe they're just being foolish or old-fashioned. But they may also be on to something.

Mike Tanier covers the NFL for Bleacher Report. Follow him on Twitter: @MikeTanier.