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Patrick Mahomes screamed. He threw down his helmet in anger. The Kansas City Chiefs’ MVP quarterback lost his composure on the sideline at Arrowhead Stadium to a degree unseen previously. He was apoplectic.

Never before could Mahomes recall losing a game on an officiating call like the one referee Carl Cheffers’ crew made to negate a go-ahead Chiefs touchdown. Mahomes had shrugged off a blatantly bad missed pass-interference call in Green Bay just one week ago, but offensive offside to wipe out a Travis Kelce improvised lateral TD in the final 90 seconds of a 20-17 home defeat to Buffalo? This was too much.

If any team was supposed to run hot and melt down in a narrow defeat with playoff seeding implications Sunday, the Sean McDermott-coached Bills were that team. Their week had bottomed out with “Saturday Night Live” parodying McDermott for citing the teamwork of 9/11 terrorists during a 2019 team meeting — one of several damaging revelations from the Go Long expose casting McDermott as an out-of-touch, unaccountable micromanager.

Since when do the Chiefs lose the way the Bills are supposed to fall short? Since now, is when. Because the margin for error has evaporated for Kansas City, complicating its push for another Super Bowl.

The Pick Six column sizes up where the Chiefs stand, why their margin for error is gone and what it could mean for the future, with a Dan Marino career parallel to keep in mind, even if it’s premature now. As for the penalty Mahomes and the Chiefs were so upset about, we’ll get to the bottom of that one as well, with insights aplenty from NFL contacts.

• Mahomes, Chiefs and Dan Marino
• Offensive offside? Here’s the deal
• Zach Wilson, Justin Fields audition
• MVP update: Case for Tyreek Hill
• On Packers’ 16-0 December record
• Two-minute drills: Sam Howell’s future

1. Here is where the Chiefs stand, why Dan Marino is relevant, thoughts on Travis Kelce and the new reality at wide receiver.

Mahomes’ starting record before Sunday was 46-2, counting playoffs, when Kansas City held the opponent below 21 points, per TruMedia. That included 16-2 when the opponent scored 17-20 points.

Those records are now 46-3 and 16-3, respectively. Both previous defeats were oddities against the Indianapolis Colts in 2019 and last season. This one hurt more because it more accurately reflected where the Chiefs stand on offense. This was less of a one-off than those Indy games. It was the game after the Chiefs lost 27-19 in Green Bay, which was two weeks after the Chiefs lost at home to Philadelphia, which was two games after the Chiefs lost to a Denver team that didn’t even try to play offense.

Where the Chiefs stand: The chart below shows AFC teams’ week-to-week probability changes as they chase the top seed in the conference, a first-round bye and home-field advantage throughout the conference playoffs.

The Athletic’s Austin Mock maintains the model used for the projections. By his accounting, the Chiefs’ chances have plummeted from 60 percent entering Week 11 to 11 percent now, well below the Miami Dolphins (53 percent) and Baltimore Ravens (34 percent).

“I’d be worried about them on the road against Miami,” a coach with AFC East experience said. “You are going to Miami, and it is going to be hot as hell, as opposed to bringing Miami into Kansas City and it’s freezing? That is a big difference.”

I think the Chiefs will win out against the Patriots, Raiders, Bengals and Chargers, but they aren’t facing any of those teams in the playoffs.

The Marino warning: Mahomes has played 11 postseason games at home, three at neutral sites (Super Bowls) and zero on the road. That has helped him win two championships in his first five seasons as the Chiefs’ starting quarterback. Now that the Chiefs’ Super Bowl path is likely to take them outside Arrowhead, it’s a good time to consider historical precedent.

Per Pro Football Reference, Mahomes is one of 34 quarterbacks since 1950 to start at least 10 postseason games. Of those quarterbacks, Mahomes and Marino are the only ones to make their first six playoff starts at home or in the Super Bowl.

Marino used that early edge to reach the Super Bowl in his second season. But he played seven of his remaining 11 playoff games on the road, including six of his final seven, and never reached another Super Bowl. For his postseason career, Marino finished 7-3 at home, 1-6 on the road and 0-1 at neutral sites.

While there is every reason to expect Mahomes and Andy Reid to reach future Super Bowls, and I would never bet against them, there was every reason to think Marino and Don Shula would reach more of them as well.

The path becomes more complicated in the absence of home-field advantage, for two reasons.

Beyond the challenges associated with road games, the lower-seeded teams that must travel simply aren’t as good as higher-seeded teams that stay home. If the Chiefs find themselves on the road this postseason — and more frequently in future postseasons as Kelce declines and eventually retires — it’ll be because they aren’t as good in the future as they’ve been in the past. Which now appears a little more likely.

The Kelce question: From 2010 into 2015, Tom Brady’s touchdown rate was about twice as high when tight end Rob Gronkowski was on the field, compared to when Gronk was not playing. There were times when the New England offense struggled to function without him.

Mahomes feels at least as reliant on Kelce as Brady was on Gronkowski. The difference is, Kelce has not missed many games, so we haven’t seen what the offense looks like without him (I’m picturing the 2019 Patriots, but if Brady were mobile). We have seen Kelce’s production decline along with the production of the offense, and so we wonder which one is affecting the other most, especially now that Kelce is 34.

“It is funny you say that,” a general manager from another team said. “I was watching him run down on that Hail Mary (against Green Bay), and I was thinking he might be almost done. I say that understanding he has been productive at times this year. But you know what the first sign of decline for a player like Travis Kelce is? That he is not the same player late in the season. It means his body is not recovering.”

Kelce is averaging 11.2 yards per reception, a career low. Respect for him still runs high.

“Kelce is fine,” an offensive coach countered. “He has never been good lining up and beating a guy press-man on him, but they do such a good job of moving him, motioning him, change-release routes, and a lot of catches come on Mahomes’ scrambles when people lose track of him.”

Former NFL GM Randy Mueller has called Kelce the best he’s ever seen at finding soft spots in zones. He thinks there’s too much pressure on Mahomes and Kelce to carry the offense, and not enough help from the wide receivers, especially now that Kelce is older. Which brings us to our final point.

The receivers aren’t good enough: With the game on the line Sunday, the Chiefs pulled off an all-time great play. Mahomes threw downfield to Kelce for a 25-yard gain. Kelce threw the ball backward to Kadarius Toney, who ran into the end zone for the go-ahead touchdown with 1:25 remaining. It should have been an epic moment in Chiefs history. But there was a flag on the play. Replays showed Toney lining up offside. The penalty was a killer.

Play was called back but can’t believe Kelce tried this 😮 📺: #BUFvsKC on CBS📱: Stream on #NFLPlus https://t.co/pWMED8SAQa pic.twitter.com/LREwwhaQ1N — NFL (@NFL) December 11, 2023Mahomes was irate, but let’s zoom out for a moment and consider the situation objectively. With a realistic shot at the AFC’s No. 1 seed on the line, the Chiefs were only as strong as their weakest link. They were betting on a receiver deemed expendable by the New York Giants, who have been desperate for production of any kind at the position. If Toney were a seasoned pro known for his attention to detail, the…