PITTSBURGH — It was nothing new, really. The only thing different was the result.

For the past two months, the Giants relied on their stingy defense to keep them in games while their sputtering offense scored just enough points to beat some very bad teams. It was a formula that allowed them to win six straight and become a legitimate contender not only for a playoff berth but for the NFC East title.

On Sunday, though, the formula became a serious flaw.

The Giants managed only one touchdown while the game was competitive — and that came on a 17-yard drive after a defensive takeaway — and were unable to keep up with the Steelers in a 24-14 loss at Heinz Field.

After they ran over a string of also-rans, the first team the Giants faced with a winning record since Nov. 6 proved to them that they will not be able to win these kinds of games without getting their offense on track.

“Offensively, we didn’t do enough,” running back Rashad Jennings said. “We’ve been able to get away with it. Today we didn’t. It’s good for us to take that medicine.”

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It is, as long as it cures the ills. The Giants have four games remaining to make the postseason for the first time since 2011.

The loss puts the NFC East title further out of reach for the Giants (8-4), who will face the first-place Cowboys (11-1) on Sunday night at MetLife Stadium. The Giants remain in control of a wild-card berth, but they’ll face the gantlet of Detroit, Philadelphia and Washington after the Cowboys.

Defensive end Olivier Vernon said last week that the Steelers game, a clear step up in class, would allow the Giants to “see what we’re about.” The verdict?

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“We have to play better,” he said. “We knew coming into December it would be basically playoff football. We have to win in December.”

That it continues to be the offense that holds them back remains a perplexing problem.

“We are who we are right now,” Ben McAdoo said of a group that has yet to score 30 points in a game this season. “You can’t just flip a switch and have things change.”

Yet that’s exactly what the Giants need now. After 12 weeks of assurances that a breakout is on the way and production is around the corner, there now are four games left to have it happen.

McAdoo said he is not concerned about the possibility that it might never click this season. “You have to put work into it,” he said. “It has to pay dividends for you. We’re working at it.”

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Jennings, too, insisted there is time to turn things around.

“We got four games,” he said.

The Giants had five coming into Sunday and squandered the first one. They managed only 91 yards in the first half, gave up a safety on Ereck Flowers’ holding penalty in the end zone and trailed 14-0 at the break.

Their best drive of the half brought them all the way to the 9, but Eli Manning threw an interception while trying to get the ball to Larry Donnell in the end zone. Lawrence Timmons returned the pick to the Giants’ 40 to set up a Steelers touchdown.

“I tried to squeeze it in there,” Manning said. “I thought if I could get it high enough . . . and kind of put it on that back shoulder a little bit. Lawrence Timmons got a little wider than I thought.”

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The Giants failed to convert a fourth-and-1 from the 3 early in the third quarter, but Jona than Casillas forced a fumble that Eli Apple recovered to set up the Giants’ first touchdown, a 13-yard pass to Jennings. The Steelers responded with a touchdown drive to go up 21-7.

The defense gave the offense another crack at it late in the third when Apple pulled in an interception. The Giants didn’t get any points off that one, though, giving the ball back on Manning’s second interception on a desperation fourth-and-13 attempt from the Steelers’ 35 with 11:23 remaining.

“We tried everything to change the momentum and get the offense back the ball,” safety Landon Collins said of the two third-quarter turnovers the defense forced. “I thought it was going to make a difference in the game. That’s where the offense has to put points on the board.”

They didn’t. They haven’t. All year long.

“You win as a team, you lose as a team,” Vernon said of any building frustrations by the defense over the lack of scoring. His side of the ball played well enough to win this game and show that it can be considered among the elite units in the league. The other side has yet to demonstrate that.

“We’re good enough to compete,” Manning said of the stretch run. “Defense is playing well, offense is going to make our plays and get some big plays.”

The season is depending on it.