The NFL never allows you to rest easy, never lets you assume anything. The stakes of Week 18 appeared simple. The Indianapolis Colts would obviously take care of the woeful Jacksonville Jaguars, and then Sunday night the Las Vegas Raiders and Los Angeles Chargers would clash in a de facto playoff game.

But the Jaguars took an early lead, the Colts kept falling further behind, and a slew of possibilities burst forth. The playoff field was set in a way nobody saw coming, in a way that turned fans in Las Vegas and Pittsburgh and New Orleans and Los Angeles and other places into puddles of stress from 1 p.m. to past midnight. Here is what to know.

Carson Wentz and the Colts blew a playoff spot in epic fashion. All the Colts had to do last week to clinch a wild-card spot was beat the Raiders at home as 7½-point favorites. They lost, but all they needed to do Sunday was beat the lowly Jaguars on the road as 15½-point favorites. They not only lost to a team that was 3-29 in its previous 32 games and lost by 40 points last week. The Colts were blown out.

How in the world did the Colts lose, 26-11, to the Jaguars after trailing by 23 in the fourth quarter? It was a complete meltdown. The Jaguars’ defensive line whipped the Colts’ offensive line. Jacksonville quarterback Trevor Lawrence closed a dispiriting rookie season by playing like the surefire No. 1 pick. Weird things happen when cold-weather teams travel to Florida’s heat and humidity late in the season. The Jaguars proved for the millionth time that you bet against the competitive pride of professional athletes at your own peril.

But the primary reason the Colts will spend the postseason at home is that quarterback Carson Wentz was not nearly good enough. Last week, Wentz completed 16 of 27 passes for only 148 yards. On Sunday, he was worse. He completed 17 of 29 passes for 185 yards with an interception and a lost fumble and took six sacks. The Colts acquired Wentz to push a strong roster into Super Bowl contention. Now they have missed the playoffs in embarrassing fashion, and they will have to ship a first-round pick to the Philadelphia Eagles. Instead of solving their quarterback problem, the Colts created a new one.

The Jaguars, meanwhile, were rewarded by the football gods for their effort. They maintained their hold on the No. 1 pick after the Detroit Lions, who received another upbeat performance on behalf of Dan Campbell, beat a Green Bay Packers team that rested starters in the second half.

The Raiders and Chargers played for the heavyweight championship of each other. They could have mutually assured a playoff bid through a tie, which would have bounced the Pittsburgh Steelers from the postseason. Even in overtime, neither team showed interest in anything but winning. The players and coaches had dedicated their lives to winning, and they could not keep from playing to win even when it went against their self-interest.

At the end of an epic, the Raiders could have run the clock out and guaranteed a playoff berth. “We knew, no matter what, we wanted to win,” quarterback Derek Carr said in an NBC interview. “We didn’t want to tie.”

Interim coach Rich Bisaccia sent kicker Daniel Carlson on to the field even though a blocked kick could have jeopardized their season and a make would barely change their fate. Carlson banged through a 47-yarder that knocked out the Chargers and brought jubilation in Pittsburgh. The Raiders will benefit by playing the Cincinnati Bengals instead of the Kansas City Chiefs next week.

The Raiders had blown a 15-point fourth-quarter lead. They had absorbed a 19-play drive from the Chargers that included three fourth-down conversions, a barrage of inhuman throws by Justin Herbert and a 12-yard touchdown pass with no time on the clock.

For the Raiders, that was nothing. Jon Gruden had resigned after an email scandal. Wide receiver Henry Ruggs III had been charged with DUI after a deadly car crash and released. On the field, they won their last four games by two, two, three and three points.

It was a bitter result for the Chargers, who had more than enough talent to make the playoffs and do some damage. Herbert is young, but missing the playoffs with a star quarterback on a rookie contract is an opportunity squandered.

The Steelers walked through the door that the Colts’ loss opened. The first line of Mike Tomlin’s Hall of Fame plaque should read, “Made the playoffs with 39-year-old Ben Roethlisberger.” The Steelers were outscored by 55 points this season and played with a stationary quarterback who lost his arm strength a presidential administration or two ago. Somehow, Tomlin guided them to the playoffs after the Colts blew it and a 16-13 overtime victory in rainy Baltimore nudged their record to 9-7-1.

The Steelers are not bereft of talent, especially on defense. T.J. Watt tied Michael Strahan’s single-season record of 22.5 sacks when he dropped Tyler Huntley on Sunday. Minkah Fitzpatrick is one of the league’s best, most versatile safeties. Cam Heyward, a stalwart on Pittsburgh’s defensive line, submitted his best season. But the Steelers do not look like a playoff team anywhere but in the standings — and even then they had to sweat a tie in Chargers-Raiders until the clock ticked past midnight.

“Man, we got a lot of warts,” Tomlin said. “But we’re here.”

Patrick Mahomes is a buoy. If the NFL could not sink this iteration of the Chiefs this season, then when will it? Kansas City, coming off a crushing Super Bowl loss, started 3-4 and reached a near-crisis regarding its ability solve a specific set of defensive tactics. Mahomes strung together several of the worst performances of his career. They still won 12 games, claimed the AFC West for the sixth straight season and seized the AFC’s No. 2 seed.

With Mahomes and Coach Andy Reid, the Chiefs have replaced Tom Brady and Bill Belichick as the AFC tandem that effectively guarantees contention year in and year out. Mahomes adjusted to his rebuilt offensive line, grew more patient against looks with two deep safeties and dominated in a 9-1 finish.

The Chiefs are the favorite in the AFC for the third straight season, even as a second seed that lost to the top-seeded Tennessee Titans by 24 points in late October. They received another break when the chaos of Week 17 gave them the Steelers — a team they throttled, 36-10, three weeks ago — instead of a more formidable first-round opponent. Their position is a testament to the underlying lesson of their season: What happens to Mahomes early in the season almost doesn’t matter, because we know where he’ll end up at the end.

The Los Angeles Rams are limping into the playoffs. The Rams entered Week 18 on a five-game winning streak and yet were still unsettled. Matthew Stafford had spewed turnovers in consecutive close games against middling opponents. Defensive backs Jalen Ramsey and Taylor Rapp had gotten into a physical altercation last week. They seemed on their way to a stabilizing victory that would clinch the NFC West title when they went up 17-0 on the San Francisco 49ers. It only led to their most troubling loss yet.

The Rams blew their lead as the 49ers ran the ball down their throats in the third quarter. The Rams retook the lead at 24-17 thanks to Ramsey’s acrobatic interception and Cooper Kupp’s dazzling touchdown catch. The 49ers could not answer, and the Rams received a punt with 1:57 remaining in the fourth quarter. The 49ers forced a three-and-out, then drove 88 yards without any timeouts to force overtime. San Francisco kicked a field goal on the opening possession, and Stafford threw a game-ending interception on a misfired deep ball to Odell Beckham Jr. 49ers 27, Rams 24.

Los Angeles dropped from the No. 2 seed to the No. 4 spot, but it still won the West because the Arizona Cardinals lost to the Seattle Seahawks. For a team whose season will end with a Super Bowl appearance at home or in failure after the splashy, resource-draining moves it made, it has been a disappointing stretch.

The one unimpeachable part of the Rams remained Kupp, who won the receiving triple crown during one of the great seasons in NFL history. He led the NFL with 1,947 receiving yards — 17 shy of Calvin Johnson’s record — on 145 catches with 16 touchdowns. Aside from Kupp, though, the Rams can’t feel great about the way they finished the season.

Jimmy Garoppolo isn’t going away quietly. Garoppolo has faced more doubts than any starting quarterback in the playoffs — starting with his own franchise, which traded up to draft Trey Lance with the third pick in April. One thing that can’t be questioned is Garoppolo’s guts.

Garoppolo held on to his starting job all season when healthy, and Sunday he played with a barely healed torn ligament in his thumb, a black wrap around his throwing hand. Despite the 17-0 deficit, Garoppolo led the 49ers back and then steered them 88 yards in about a minute with no timeouts, hitting Jauan Jennings for the game-tying touchdown.

The 49ers’ victory nudged the New Orleans Saints, who finished 9-8 after a victory over the Atlanta Falcons, out of the playoffs. The Saints’ season started with a hurricane moving them to Fort Worth. They started four quarterbacks, including overwhelmed rookie Ian Book. Alvin Kamara missed a handful of games. And they still came within a few plays of going to the playoffs. Sean Payton sure can coach.

The coaching carousel started to spin. The Denver Broncos fired coach Vic Fangio on Sunday morning, a day after a season-ending loss to Kansas City finalized their record at 7-10 and 19-30 during Fangio’s three seasons. Fangio authored a remarkably forgettable tenure, posting middling records behind deficient quarterbacks. But he will be among the most coveted coaching free agents for his services as a defensive coordinator, the position in which he excelled with the Chicago Bears before his move to Denver.

Fangio soon will have company in looking for a new gig. The Jaguars are already looking for Urban Meyer’s full-time replacement. The Chicago Bears are expected to move on from Matt Nagy. Mike Zimmer could be on shaky ground in Minnesota after two straight 7-9 seasons.

The New York Giants were reportedly committed to bringing back Joe Judge, but his debacle of a finish in both words and results — not to mention a 10-23 record — will give them no choice but to consider his future. The Houston Texans are reportedly considering David Culley’s job status, even though he took a decrepit roster and provided a platform for Davis Mills’s promising rookie season. There could always be a surprise — perhaps the Seahawks are ready for a fresh start after a rare losing season from Pete Carroll.