Teams don’t suddenly turn into champions when the postseason begins. If anything, the even matchups and heightened stakes force opponents to rely more heavily on what they’ve done best all year since there’s little room for experimentation.

The Bills have followed quarterback Josh Allen’s daring to the postseason, riding the risk roller coaster the whole way. On the first weekend of the 2022 N.F.L. playoffs, Buffalo didn’t stray from that routine, and it almost gave the Miami Dolphins an upset. Meanwhile, the Giants used a savvy defensive game plan to beat the Vikings, and the Jaguars leaned into the resilience they’ve shown all year to take down the wobbly Chargers.

Josh Allen’s big plays cut both ways.

Allen giveth, and Allen taketh away. One of the league’s most prominent big-play makers, Allen had the most volatile game of his season in Sunday’s 34-31 win over the Dolphins. The deep throws and extended plays that buoyed an otherwise hapless Buffalo offense were the same plays that led to turnovers and disjointed drives. It was a game that highlighted both Allen’s singular ability to affect a game and also how dangerous his decision making can be for the Bills.

Allen started the game firing on all cylinders. On Buffalo’s second drive, Allen strung together two improbable throws to bail out the Bills and eventually score a touchdown.

The drive began with a 20-yard pickup, but the Bills quickly faced a third-and-15 near midfield — a classic case of the conundrum Allen presents to defenses. Not blitzing gives him too much time to find an open receiver for a chunk play, but blitzing Allen opens up the possibility that he’ll break the pocket on a run or find an uncovered receiver.

The Dolphins chose to roll the dice on an all-out Cover 0 blitz, and they paid for it. Bills receiver Stefon Diggs beat defensive back Xavien Howard one-on-one down the field, and Allen nailed Diggs for a 52-yard gain. On the very next play, Allen scurried to his right to pin a touchdown pass just past the helmet of a Dolphins defender and into the outstretched arm of tight end Dawson Knox for the first score of the game.

By the next quarter, Allen couldn’t stop himself from playing so aggressively. Offensive coordinator Ken Dorsey continued to dial up shot plays, and Allen had zero reservations about taking them, a strategy the Dolphins eventually wised up to.

With 6:01 to go in the second quarter, the Bills called a first-and-10 play-action deep shot near midfield with receiver John Brown sprinting down the sideline. Brown never had the step on his man; Howard, whom Diggs had burned for the earlier long pass, was on top of Brown the whole way. Allen let it rip anyway, coughing up a senseless turnover when both of his underneath check-down options — running back Devin Singletary and tight end Quintin Morris — were open.

Allen was stuck in big-play mode from the beginning of the second quarter to the middle of the third. The Dolphins outscored the Bills, 24-3, over that stretch, including a strip-sack touchdown of Allen. Allen finally recovered by leading back-to-back touchdown drives that included a dazzling Cover 2 hole shot to Gabe Davis for a touchdown, the kind of throw that reminded everyone watching that it’s still Allen’s game to decide.

That’s been a scary way for the Bills to play this season, with their three losses each featuring Allen turnovers. Allen finished Sunday’s game with 16 interceptions and 22 giveaways this season, including the playoffs. That’s tops in the league, according to N.F.L. Research (at least until Dak Prescott plays on Monday).

Perhaps Allen wouldn’t be tempted to gamble if the Bills had a more consistent running game, and if the team regularly threw more in the short area and chipped away at drives. But Buffalo has banked on Allen’s unique eye and talent for doing the improbable. And on Sunday, a Skylar Thompson-led Dolphins team couldn’t make the Bills pay. Buffalo may not be so lucky against the rest of a loaded A.F.C. playoff pool.

The Giants won with their defense.

Defense isn’t what got the Giants to the playoffs. Injuries kept many of their best defensive players out of the lineup during the season and robbed them of the chance to build up chemistry. They finished 25th in yards per game allowed and 24th in yards per play allowed. They never quite found their footing as a unit under new defensive coordinator Don Martindale.

When the team needed them most on Sunday, however, the defense tightened up. Martindale called on the lessons he took from the last time these two teams played in Week 16, a 3-point Giants loss. The defense was most successful in that game when it played with a softer pass-rush approach and directed its coverage attention toward Justin Jefferson, often bracketing or playing Cover 2 to his side of the field.

Martindale didn’t send as many pressures at Kirk Cousins as usual, instead favoring more four-man rushes with softer coverage behind it. Per the N.F.L.’s Next Gen Stats, the Giants played a season-high 65 percent of their snaps from split-safety coverages. The Giants struggled to affect Cousins directly — he wasn’t sacked and didn’t throw any interceptions — but they took away the wide-open explosive passes he is used to finding with his receivers.

The Giants instead gave Cousins everything he wanted over the short and middle parts of the field. Slants, hitches and shallow crossers were all available, and Cousins, a by-the-book passer, took all those open short throws with enthusiasm. Tight end T.J. Hockenson was the biggest beneficiary, netting 10 catches for 129 yards. That approach can be a dangerous game, too, but the Giants’ defense stepped up when it came to tackling. Minnesota’s receivers struggled to squeeze out extra yardage, and chunk plays after the catch were tough to come by.

Martindale and the Giants’ defense weren’t exceptional, but they were enough. They lulled Cousins into dinking-and-dunking the game away, and they made sure to tackle well enough to not let the Vikings bite them in the behind. That kind of defensive fortitude is going to have to hold if the Giants want to trudge forward in a brutal N.F.C. divisional-round matchup.

Doug Pederson’s calls keyed the Jaguars’ comeback.

Trevor Lawrence’s playoff debut opened in terrible fashion, with the second-year Jaguars quarterback throwing four interceptions on the first six drives. That meltdown helped the Chargers to a 27-0 first-half lead.

Each interception was worse than the last, on throws that ranged from unlucky to wishy-washy to flat-out horrible. Lawrence’s first interception was a tipped ball on a run-pass option throw, and his second pick came on a missed ball in which receiver Zay Jones was roughed up by a Chargers’ defender with no flag thrown. Bad plays, to be sure, but mistakes that could be forgiven.

Then Lawrence threw a third interception after failing to read the defense, and he one-upped that two drives later with a throw over the middle and straight into traffic for his fourth interception.

Somehow, those mistakes — and a muffed punt return — weren’t enough to slay Lawrence and the Jaguars. Coach Doug Pederson dug deeper into his bag of tricks, and the Jaguars’ receivers stepped up in the second half. Tight end Evan Engram, in particular, took center stage in the Jaguars’ rally to victory.

The Chargers’ linebackers weren’t adept at coming downhill to tackle, and in the second half, Pederson and Lawrence found ways to make them do that relentlessly. Engram raced straight across the shallow part of the field over and over again, and Lawrence found him repeatedly on shallow throws that reaped 10- and 15-yard chunks. Lawrence and Pederson hammered that matchup until the Chargers made an effort to stop it, which finally opened up the vertical game for Lawrence.

All of the Jaguars’ efforts came to a head in the fourth quarter while trailing, 30-28. On fourth-and-1 at the Chargers’ 40-yard line, Pederson called a timeout with 1:28 remaining to get the Jaguars out of a quarterback sneak call. Pederson came out of the break with a strike of brilliance.

The Jaguars lined up in an old-school T formation — three players in a horizontal row behind the quarterback — and sent running back Travis Etienne on an outside rush to the right. Etienne hit the perimeter, made the lone cornerback miss and booked it 25 yards for a first down, putting the Jaguars at the 16-yard line for a game-winning field goal.

Around the N.F.L.

Bengals 24, Ravens 17: The Ravens played their hearts out. Defensively, they had Joe Burrow’s number. Baltimore’s well-designed pressure schemes and chippy play over the middle made it difficult for Burrow and the Bengals’ passing offense to ever get in a groove. That wasn’t enough, though. Ravens quarterback Tyler Huntley, who mostly played a respectable match, squandered the game early in the fourth quarter. After leading an 80-yard drive, Huntley reached for the end zone on a quarterback sneak. He was short by about a yard, and the ball was jarred loose right into the hands of Bengals defensive end Sam Hubbard, who ran it back for a touchdown to break a 17-17 tie. It was a mistake that ultimately sealed the Ravens’ fate.

Giants 31, Vikings 24: Both Daniel Jones and Kirk Cousins had a field day in the short area, peppering each other’s defenses with throws designed for yards after the catch. The Giants’ receivers were just a smidgen better at evading their opponents and picking up extra yardage, and that was the difference. The Giants’ speedy receivers moved the ball into the red zone regularly, and running back Saquon Barkley made sure to finish the job for them a couple of times. It’s hard to imagine the Giants have the juice to go any further than this in the playoffs, but stealing a postseason win in a “rebuilding” year with a first-year head coach is a huge success.

Bills 34, Dolphins 31: After a 17-0 start, the Bills collapsed for about a quarter and a half. Quarterback Josh Allen, great as he is, could not stop throwing the ball deep to covered defenders. A couple of those hero throws became interceptions, giving the Dolphins extra chances on offense. Miami capitalized on plenty of those chances, getting spectacular downfield throws from Skylar Thompson in between his four sacks. Allen nailed receiver Gabe Davis for a 23-yard touchdown in the fourth, and then the Bills’ defense stopped a Dolphins’ drive at midfield to end things.

Jaguars 31, Chargers 30: It’s hard to play two more different halves of football than the Jacksonville Jaguars did. Quarterback Trevor Lawrence had four interceptions before halftime, and the defense constantly folded in its attempts to slow down Justin Herbert, who got Los Angeles out to a 27-0 start. Everything flipped in the second half, when Lawrence threw touchdown passes to Zay Jones, Christian Kirk and Marvin Jones, leading the third-biggest playoff comeback in N.F.L. history. It was also the first playoff game in which a team with five more turnovers than its opponent won.

49ers 41, Seahawks 23: Rookie quarterback Brock Purdy threw for 332 yards and three touchdowns, and the 49ers scored on four straight drives in the second half, giving San Francisco a lead that allowed its pass rush to tee off on Seahawks quarterback Geno Smith (25 of 35 passing for 253 yards, three sacks). Deebo Samuel added a 74-yard touchdown catch, and Christian McCaffery had 119 yards rushing on 15 carries.