More than a few folks immersed in the NFL have concluded that San Francisco coach Jim Harbaugh is halfway through his final season with the 49ers.

His players are tired of how the former Stanford coach treats them like they’re still in college, the rumblings go. The players have quit on Harbaugh — that’s why they’ve lost four of their past seven contests after reaching three consecutive NFC title games and Super Bowl XLVII in New Orleans, the doubters contend.

Yet, as a rule, coach Sean Payton — whose New Orleans Saints (4-4) host the 49ers (4-4) at noon Sunday in the Mercedes-Benz Superdome — rejects those kinds of narratives. And he expressed a special disregard for the one painting Harbaugh and the 49ers as a group who had checked out of its campaign at the midway point.

“If you just look at (Harbaugh’s) numbers, they speak for themselves,” Payton said. “He’s done an outstanding job, and quickly. ... I just know the respect we have for him and what he’s done for that program — it’s been obviously significant.”

It’s not hard to see where Payton is coming from. Despite the .500 mark the 49ers are carrying into their latest clash with the Saints, Harbaugh’s regular-season record since he joined San Francisco in 2011 is 40-15-1 — an astounding .723 winning percentage. Harbaugh’s 49ers have won 19 of the 28 times they’ve traveled for a road winning percentage of .679 — the best of all coaches since he entered the league.

Under the command of coordinator Vic Fangio, a Saints assistant from 1986-94, the 49ers defense finished fourth, third and fifth in yards allowed. They’re No. 2 in that category this year, although they’ve been more lackluster in other phases of the game.

“We’re not where we want to be,” Harbaugh said of his team overall. “And we certainly have to approach these games as single-game seasons (in terms of urgency).”

Nonetheless, “things can change quickly,” Saints quarterback Drew Brees said. “You can’t take anything for granted.”

Brees certainly speaks from experience. His team couldn’t measure up to what the Saints perceive as the winning culture Harbaugh has installed in San Francisco in the 2011 season, when New Orleans visited the 49ers in the divisional round of the playoffs armed with the most prolific offense in NFL history but fell 36-32, one of the most traumatic losses in franchise history.

They couldn’t measure up in the 2012 regular season, when Payton was suspended in the wake of the bounty scandal and the Saints lost at home 31-21. And it took all the Saints could muster in 2013 to at last vanquish Harbaugh and the 49ers 23-20.

A couple of other things illustrate the professional respect New Orleans holds for the Harbaugh-led 49ers. For one, few regular-season victories have been as celebrated by New Orleanians in the post-Super Bowl XLIV championship era than the one the Saints scored over San Francisco last year. Also, the pair of seasons Parys Haralson spent in Harbaugh’s program factored into the Saints’ decision to trade for the veteran linebacker in response to a wave of injuries at the start of the 2013 campaign.

Haralson was a starter for Harbaugh and Fangio in 2011 before having to rehab a preseason triceps injury throughout 2012, when the 49ers made a run to the Super Bowl. After being dealt to New Orleans for a seventh-round draft pick, he has become a valuable contributor in both run-defending and pass-rushing situations for the Saints.

Payton this week attributed some of that to his time in San Francisco.

“I like the fact that he (was) coming from a winning program,” Payton said. “He understands the importance of preparation. He understands the details and how difficult it is to win. He was a solid fit for us.”

Haralson this week explained that his being around Harbaugh for a couple of years only helped his integration onto a Saints team that since early 2010 has won a Super Bowl title and has been to the playoffs three times.

“It was a lot like here: The guys here are used to winning, they play for each other. Everybody wants to do their job to help the team win,” Haralson said.

Saints center Jonathan Goodwin also has an inside perspective on Harbaugh. After playing for New Orleans from 2006-10, he spent three seasons with the 49ers before returning to the Saints in June. Goodwin said the most important piece of knowledge he could share about Harbaugh is that he definitely has figured out the whole winning thing in the NFL, and any supposed disarray doesn’t change that.

“I have nothing but a lot of respect for (Harbaugh),” Goodwin said. “In this league, all that matters is whether you win or lose.”

Harbaugh has done a lot more of one than the other, and that makes him a dangerous adversary as Sunday’s kickoff approaches.