For more than a month, as they won four successive games, the Giants went from somnolent to startlingly successful, having a stretch that resurrected the team’s fan base and advanced the budding folk hero status of the rookie head coach Joe Judge. But on Sunday, with a meaningful chance at home to maintain the momentum necessary to finish a late-season run at a playoff berth, the Giants collapsed.

Thoroughly outplayed in every facet of the game, the Giants were trounced by the visiting Arizona Cardinals, 26-7. The Giants (5-8), who never seriously threatened to upend the Cardinals, had five fumbles — three that they lost — and managed just 10 first downs and 159 total yards. Quarterback Daniel Jones, returning from a hamstring injury that had sidelined him for the last game of the win streak, was sacked six times, completed just 11 passes and left the game in the fourth quarter with a pronounced limp.

Defensively, the game was just as lopsided. The Cardinals (7-6) converted 39 percent of their third downs and rushed for 159 yards. Led by the ever-inventive quarterback Kyler Murray, who thwarted the Giants’ pass rush with his agility and knack for extending plays, Arizona earned a valuable win to keep alive their meager postseason chances.

Since the Giants were coming off an emotional upset victory at Seattle last week, it was easy to wonder if they were overconfident as they took the field against Arizona, which had lost its three previous games. That the Giants could feel comfortable looking past any N.F.L. team is somewhat comical — the franchise’s last playoff win was nine seasons ago — but there was no denying the substandard execution and attention to detail in Sunday’s debacle at MetLife Stadium.

“I don’t think we had any kind of a hangover from last week,” Judge said afterward. “We simply didn’t coach well enough or play well enough. That’s the hard truth of it.”

Nonetheless, the opportunity lost with three remaining games in a regular season that began with seven defeats in the first eight games was obvious to all.

“It’s a tough moment; we didn’t perform the way we needed to,” said linebacker Blake Martinez, one of the team’s veteran leaders. “I don’t think it was overconfidence, we just didn’t play collectively well as a team.”

And yet, when asked if the loss might serve as an alarm for the Giants, Martinez answered: “Any time you lose, it’s always a wake-up call. The really good teams focus on getting better the following week.”

The Giants will host the Cleveland Browns (9-3) next week.

For the Cardinals, whose linebacker Haason Reddick set a franchise record with five sacks — mostly by zooming past the Giants rookie left tackle Andrew Thomas — the victory was a necessary boost. Noting that his team had “a sense of urgency,” Arizona Coach Kliff Kingsbury added: “We made a step in the right direction — we understand what’s in front of us and what we can be. This will build our confidence moving forward.”

The Cardinals opened the scoring with a 34-yard Mike Nugent field goal in the first quarter shortly after the Giants’ highlight of the game — a goal-line stand by the defense that followed a Jones fumble on the team’s first possession. Jones’s turnover track record does not merit a defense but, in this case, the fumble occurred as he was being sacked by the former Giants linebacker Markus Golden, who dashed into the Giants backfield unblocked on a blitz. Jones never saw Golden coming.

As the Giants’ feeble offense failed to advance into Arizona’s end of the field in the first half, the Cardinals seemed to always be in Giants territory. But the Giants’ defense was mostly stout and Arizona was only able to extend its lead to 6-0.

When the Giants’ fatigued defense trotted off the field after forcing the second Nugent field goal midway through the second quarter, they were soon dragging themselves back into action when Giants kickoff returner Dion Lewis fumbled and gave the football back to the Cardinals at the Giants’ 21-yard line. Lewis’s turnover was forced by Arizona’s Kylie Fitts, who kicked at the football in Lewis’s arm as he ran past the Giants returner. While it is illegal for a player to kick another player, the game officials did not throw a flag for the violation and Fitts’s leg knocked the ball loose. In this case, the foul committed by Fitts was not reviewable by the referee.

Four plays later, on a third-and-goal from the Giants’ 7-yard line, Murray was backpedalling from the Giants’ pass rush when he hoisted a high pass into the end zone. Initially, it appeared that Murray was throwing the football away, but the Cardinals’ 6-foot-5 tight end Dan Arnold leapt above the crowd of four defenders to catch the throw in the back of the end zone for a touchdown that put Arizona ahead, 13-0 at the half.

If the Giants’ first half was bad, the second half was worse. After receiving the kickoff to begin the third quarter, Murray led Arizona on an 11-play, 77-yard drive that concluded with Kenyan Drake’s 1-yard touchdown plunge. The Giants answered with their only score of the game, a 1-yard touchdown run by Lewis. But Arizona dominated the fourth quarter in every way, especially with a four-man rush that repeatedly overpowered the Giants’ offensive linemen and knocked Jones to the ground so often he was pulled from the game for backup Colt McCoy, who was sacked twice.

Jones at that point was also nursing an injury. After the game, Judge said he did not know what Jones’s injury was and he defended his second-year quarterback. Asked about Jones’s erratic play, Judge answered: “There are 11 guys on the field. It’s not one person’s fault.”