The New Orleans Saints defense has drawn the brunt of the blame this year.

And rightly so: New Orleans’ defensive rankings have been unsightly, particularly during the three-game stretch that led to Rob Ryan’s firing at the opening of the bye week.

But the offense should not escape criticism. New Orleans ranks third in the NFL in yards per game and 13th in scoring, but at times the Saints have struggled to score — never worse than last week’s dud in Houston, the first time in the Sean Payton and Drew Brees era that the Saints failed to score a touchdown.

Now, heading into Sunday’s 3:25 p.m. kickoff against the undefeated Carolina Panthers in the Mercedes-Benz Superdome, New Orleans is in an offensive rut, having scored just 27 points in its past 10 quarters against Houston, Washington and Tennessee.

“It was pretty obvious all of us have to look closely at ways to improve that,” Payton said. “We really haven’t. I’d go back to the second half of the Titans game offensively in the second half of that game, and in Washington, and now this game really not playing good football. Not playing nearly as good as we are used to. That starts with me and us getting a good plan together.”

New Orleans has struggled in more than just the past three games offensively. In the Saints’ four wins, New Orleans is averaging 470 yards and 34 points per game, exactly the kind of explosive offense expected out of the Saints.

But in the Saints’ seven losses, New Orleans is averaging just 361.9 yards and 17.9 points. The Saints have broken the 20-point mark in a loss only twice this season.

Payton and Brees believe the root of the Saints’ offensive problems is on first and second down.

“If you just took the third-and-long situations that we have been in the last three weeks — it’s been far too many — and you point to first and second down efficiency, you point to penalties and other things that were negative plays that were drive-killers,” Brees said. “Those are the things that need to get fixed and will get fixed.”

New Orleans has produced an inconsistent rushing attack despite arguably the best season of Mark Ingram’s career, ranking 21st in the NFL in yards (96.6 per game) and yards per carry (3.9).

The Saints have been equally inconsistent on the ground in wins and losses. New Orleans is averaging 4.0 yards per carry in wins, 3.9 per in losses.

Numerically, the biggest difference for the Saints offense this season has come in the passing game.

New Orleans’ completion percentage is 74.9 percent in wins and 65.1 in losses, while yards per attempt drops from 8.3 to 7.5. New Orleans has given up 20 sacks in the seven losses to just six in the four wins, and the Saints’ touchdown-to-interception ratio is 9-to-8 in losses as opposed to 11-to-3 in wins.

But the raw numbers don’t indicate that Brees is playing worse than he has in the past. He has completed 68.1 percent of his throws for 3,200 yards, 20 touchdowns and 10 interceptions.

“I think he is throwing it better this year than a year ago,” Payton said.

A big problem has been putting Brees in untenable situations, particularly third-and-long.

New Orleans has given up 16 of its 26 sacks on first down, the Saints’ inconsistencies in the running game has put New Orleans in difficult situations and penalties have cost the Saints dearly on first down.

“Some of it’s just simple execution; maybe it’s one guy here or there,” offensive coordinator Pete Carmichael said. “(Payton’s) right, because we’ve struggled with some first- and second-down executions, and instead we find ourselves in third-and-9 (or) -10 (or) -12. Those just are not favorable positions for any offense.”

A third-and-long situation allows opposing pass rushers to tee off on Brees.

“When you’re into these third-and-longs, obviously (protecting the passer) becomes much more difficult,” Payton said. “I think it’s part of the challenge and part of the reason we have struggled, and yet there is a bigger byproduct from it, and it’s the early-down efficiency.”

The sacks allowed discrepancy could be ascribed to the fact that the four teams the Saints have beaten — Dallas, Atlanta, Indianapolis and the New York Giants — all rank 25th or worse in the NFL in that category on defense.

New Orleans jumped to big leads on all four of those teams. Only four of the Saints’ sacks have come when New Orleans was winning. Fifteen sacks were recorded when the Saints were trailing.

In addition, sacks are an imperfect way to judge a team’s pass protection. Even if the opponent isn’t sacking Brees left and right, it can affect the Saints passing game by hitting him repeatedly and forcing hurried throws.

“Obviously, I don’t think the pass protection’s been good enough,” right tackle Zach Strief said. “And again, show me the score in the fourth quarter, and I’ll show you how the pass protection’s going to finish out. ... We’ve had games where we gave up three sacks and I’d say the protection was good, and we’ve had games — I’d say the protection (against the Texans) wasn’t great, and we gave up two. We’ve given up more with less consistency. So much of it for us as linemen is, ‘Are you productive in the run game early?’ ”

Brees said he believes he should be able to get rid of the ball regardless of pressure.

“There are times where you’re going to get pressured, and maybe they’re just bringing more than you can protect and then you have to know when to get rid of the ball,” he said. “There are times where we are just going to get beat, and you just have to know when to get rid of the ball. There are times when they are just going to get you. You just have to be able to move on and overcome it.”

The passing numbers in wins and losses are skewed because Brees has to take more chances when he’s trying to make up a big deficit in the fourth quarter. The Saints’ passing numbers go way down in the fourth quarter — New Orleans has thrown 10 of its 11 interceptions in the second half — but that has more to do with the score than the game clock. New Orleans also has tossed seven interceptions while trailing and trying to come back.

“You have to take chances,” Brees said, “and you have to be more aggressive.”

Boiling everything down, New Orleans has to find a way to start faster, both on every series of downs and in the game overall.

All of the Saints’ passing numbers are better in the first half and when the Saints have the lead.

And to start fast, New Orleans can’t dwell on the offensive struggles of the past three weeks.

“We have to remain confident,” tight end Benjamin Watson said. “One of the hardest things to do is, when you have a couple of games that don’t go your way, your confidence starts to wane. So confidence, both individually as football players and also collectively, we have to understand: We have good plays, and we have good players. We’ve obviously, the early part of the season, done fairly well, haven’t done as well the last few games, but that doesn’t mean we can’t get back to where we need to be.”

One of the NFL’s best defenses will be waiting in the Superdome on Sunday. New Orleans better get back on track quickly.