Five things that stood out about Chiefs’ loss in Buffalo that halts undefeated run

The undefeated season is gone.

The race for the AFC’s No. 1 seed is very much alive.

The Bills beat the Chiefs 30-21, the legs of Josh Allen besting the arm of Patrick Mahomes.

The Chiefs lost for the first time in 11 months. And, just like that, their place atop the AFC becomes wobbly. They are just one win up on the Bills.

Here are five observations from immediately after the game:

1. Josh Allen: the runner

He’s good, man.

And, guess what, the Bills left him on the field to make a play.

Facing a fourth down, Bills coach Sean McDermott had two choices: Put the ball in the right hand of Patrick Mahomes with the game on the line, or give it to Josh Allen.

The choice: Allen.

The ballgame: On Allen’s legs.

Allen scrambled and knifed through the Chiefs’ defense on their worst day in nearly two years, scoring a game-sealing touchdown from 26 yards.

It’s a theme.

Allen has averaged 56 rushing yards per game in his eight matchups with the Chiefs — that’s 20 more than against all other teams.

That’s not just commentary on the Chiefs’ defense. We’ve seen opposing quarterbacks put their bodies on the line in ways that illustrate the importance of beating Kansas City.

2. The defensive hitch

There’s a dent in the otherwise relatively shiny armor of the Chiefs’ defense.

Third down.

And for Sunday, let’s get more specific: third and long.

The Chiefs couldn’t get off the field in the situations that are easiest to get off the field, at least relatively speaking.

The Chiefs allowed the Bills to convert four third downs of at least 7 yards — and conceded two more by penalty. That’s six times when they backed up Buffalo on first and second down and turned it meaningless on third down.

And let’s address the why, too: With Jaylen Watson out, the Bills picked on the Chiefs’ cornerback options in Nazeeh Johnson and Chamarri Conner. It’s a thing.

3. Xavier Worthy’s day

The Bills are pretty content with their first draft selection last spring — Keon Coleman at the top of the second round — but he’ll always have an interesting connection with the Chiefs.

The Bills and Chiefs made a draft-night swap that placed the Chiefs at 28th overall, where they took Xavier Worthy.

So, naturally, 10 games into the year, Worthy’s best single drive of a game came in Buffalo. He had four catches for 61 yards and a touchdown on one drive in the first half alone.

But then, well, where was he?

Worthy did not catch a single pass the remainder of the game — and there was certainly at least one opportunity.

Worthy sprung open on a deep route toward the sideline. Mahomes didn’t make the best throw, sending Worthy too close to the sideline, but Worthy should have been able to drag his back foot to secure a catch.

It’s the third time in three weeks we can use this sentence: That has to be a completion.

4. The Patrick Mahomes kryptonite

The best Patrick Mahomes drive of the season came in the fourth quarter, Chiefs trailing two possessions and having to score a touchdown.

His worst?

The first quarter.

The first pass.

I know there will be some thought that Mahomes shouldn’t have taken the risk while a defender was attempting to sack him — but, hey, that’s the description for a lot of unlikely highlights too.

I don’t mind the throw — he has to be aware the contact will affect the throw, and he just overshot Noah Gray.

It’s a trend now, and one the Chiefs need to correct. Mahomes now has a 62.9 passer rating in the first quarter this season. He’s yet to throw a first-quarter touchdown and has five interceptions.

Woof.

5. The playoff implications

The Bills-Chiefs regular season matchups have been a pretty poor indicator of future playoff results.

But for seeding? Yeah, it matters.

The Bills are only one game behind the Chiefs for the lone playoff bye in the AFC, and obviously they now own the tiebreaker there.

It’s game on.

The Bills have a boom-or-bust schedule on the back end — with dates against Detroit and a sliding San Francisco team still, but a few cakewalks to finish the season.

The Chiefs’ remaining slate is quite the opposite — a series of tough games, but they’re unlikely to be underdogs again this season.

And, yes, I know the Steelers remained at two losses after beating Baltimore for a leg up in the AFC North race. It just doesn’t change my opinion on the race for the No. 1 seed.