Through Week 5 of this NFL season, there was no team better than Kansas City. The Chiefs were 5-0 with a league-best offense in almost every major category, and they’d chalked up statement wins over New England and Philadelphia, who are now the best teams in their respective conferences. Alex Smith was the best quarterback in the game and on course for one of the greatest QB seasons in NFL history. Rookie Kareem Hunt was breaking the league as the best running back in the game, averaging more than 120 rushing yards per game and more than six yards per carry. And as we detailed, the last time the Chiefs were that good, they won Super Bowl IV. Life in the Midwest was bliss.

Few could have predicted what has happened since, though. The Chiefs’ decline began in Week 6 with a 19-13 defeat at home against the Steelers; it took a further nosedive two weeks ago when they lost to the lowly New York Giants; and it reached a nadir in their Week 12 loss to Buffalo, the latest setback in what has become one of the most mystifying breakdowns in recent memory. The Chiefs have recorded just a single win (over the Broncos) in their past six games and now sport a 6-5 record, and they have undergone the league’s third-biggest drop in Elo ratings in that time — only the Aaron Rodgers-less Packers and quarterback-less Broncos have dropped further. Fans in KC will be wondering how far their team’s performance might fall, and for good reason: This kind of collapse is essentially unprecedented. Among teams that had an Elo rating of at least 1700 after Week 5 of the season, Kansas City’s decline is the largest through Week 12 in NFL history.

Great teams don’t have meltdowns Difference in Elo after Week 5 and after Week 12 among teams that had an Elo rating of at least 1700 after Week 5 YEAR TEAM WEEK 5 ELO WEEK 12 ELO DIFFERENCE MADE PLAYOFFS 2017 Kansas City 1701 1584 -116 ? 1986 Chicago 1750 1706 -44 ✓ 1990 San Francisco 1727 1710 -16 ✓ 2015 New England 1722 1740 +17 ✓ 2007 Indianapolis 1711 1736 +25 ✓ 1994 Dallas 1705 1731 +26 ✓ 1942 Chicago 1748 1775 +27 ✓ 2004 New England 1704 1742 +38 ✓ 2011 Green Bay 1724 1772 +48 ✓ 1941 Chicago 1714 1766 +52 ✓ 1998 Denver 1712 1773 +61 ✓ 1973 Miami 1707 1771 +64 ✓ 2007 New England 1723 1806 +84 ✓ Source: PRO-FOOTBALL-REFERENCE

No prizes will be awarded for working out where KC’s problems lie. While the team’s defense has actually improved as the season has progressed — the team allowed 22.2 points per game during the 5-0 start compared with 20.8 since — the Chiefs’ offense has been woeful. Former MVP favorite Smith has received the brunt of the criticism, and rightly so: During the 5-0 start, Smith had the best passer rating in the league, but he had just the the 17th-best rating in his next six games. As for Hunt, the running back who was the favorite for offensive Rookie of the Year just a few weeks ago, his yards per carry plummeted from 6.3 in his first five games to 3.2 in his next six. As a group, the Chiefs have made another piece of forgettable history: The team’s decline on offense since Week 5 is tied for fifth-worst in the NFL since 2001.

The worst midseason dips on offense Percentage of offensive drives that resulted in a score, since 2001 RANK TEAM SEASON FIRST 5 GAMES NEXT 6 GAMES DIFFERENCE 1 Chicago 2006 50.0% 28.0% -22.0 2 Indianapolis 2007 58.0 36.4 -21.6 3 Denver 2013 57.4 36.1 -21.3 4 Denver 2008 50.9 30.2 -20.7 5 Kansas City 2017 52.8 33.3 -19.5 5 N.Y. Giants 2014 41.1 21.6 -19.5 Source: ESPN Stats & Information Group

The past month and a half has been rough for KC fans to say the least, but all is not lost. The Chiefs still have a 79 percent chance of making the playoffs, according to FiveThirtyEight’s NFL predictions, partly because the AFC West doesn’t have another team that’s above .500, and partly because just one of their remaining five opponents has an Elo rating that’s above average: the suddenly hot L.A. Chargers.

But Chiefs fans have become all too familiar with Smith’s explosive starts and dismal finishes — Smith led KC to a 9-0 start in 2013, before ending the regular season 2-5 and losing the AFC Wild Card game to the Colts. The team’s fate could rest on whether Andy Reid decides to yank Smith as the starting QB in favor of rookie Patrick Mahomes II, who the team selected with the 10th pick in the 2017 draft. In his junior year at Texas Tech, Mahomes led all FBS schools in passing yards and tacked on a 4.1 touchdown-to-interception ratio. While the first-year gunslinger would be thrust into a high-pressure environment if he takes over for Smith, Mahomes might be the spark that the Chiefs so desperately need.

FiveThirtyEight vs. the readers

Week 12 in our NFL predictions game — in which we invite you to outsmart our Elo algorithm — saw the readers beat Elo by an overall 5.5 points, just their second victorious week of the year. Their biggest individual victory came in the Chargers’ 28-6 drubbing of the Cowboys on Thanksgiving Day — readers picked up 12.4 points on that game. L.A. sits at 5-6 after two straight wins, and our model now gives the team its highest chance to date of making the playoffs — though, granted, that chance is just 26 percent. The readers had more confidence in the surging Vikings than our Elo system did, and readers were rewarded with 6.6 points after Minnesota took care of Detroit 30-23.

The biggest loss for the readers came when they put too much faith in Jacksonville (we’ve warned you before); the Jaguars fell to the Cardinals 24-27, which resulted in a 12.9 point loss for the readers. And they didn’t put enough faith in the Bengals, as Cincinnati thwarted Cleveland 30-16, yielding a 4.3 point loss for the readers.

Make sure you get your Week 13 predictions in early, and thanks for playing.

Elo’s dumbest (and smartest) picks of Week 12 Average difference between points won by readers and by Elo in Week 12 matchups in FiveThirtyEight’s NFL prediction game OUR PREDICTION (ELO) READERS’ PREDICTION PICK WIN PROB. PICK WIN PROB. RESULT READERS’ NET PTS DAL 68% DAL 56% LAC 28, DAL 6 +12.4 – DET 53 MIN 56 MIN 30, DET 23 +6.6 – TEN 52 TEN 61 TEN 20, IND 16 +5.7 – CAR 57 CAR 67 CAR 35, NYJ 27 +5.4 – KC 78 KC 74 BUF 16, KC 10 +3.5 – PIT 78 PIT 84 GB 28, PIT 31 +0.6 – WSH 68 WSH 71 NYG 10, WSH 20 +0.0 NO 55 NO 53 NO 20, LAR 26 -0.1 – NE 90 NE 90 MIA 17, NE 35 -1.1 – PHI 88 PHI 89 CHI 3, PHI 24 -1.2 – SEA 78 SEA 79 SEA 24, SF 13 -1.7 – ATL 78 ATL 78 TB 20, ATL 34 -1.9 – OAK 64 OAK 63 DEN 14, OAK 21 -2.7 – BAL 68 BAL 67 HOU 16, BAL 23 -2.8 – CIN 84 CIN 79 CLE 16, CIN 30 -4.3 – JAX 55 JAX 64 JAX 24, ARI 27 -12.9 – The scoring system is nonlinear, so readers’ average points don’t necessarily match the number of points that would be given to the average reader prediction.

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