Four times this season, reserve tackle Bryce Harris has played more than 50 snaps filling in for an injured Saints starter.

One key thing made the most recent occasion — New Orleans’ 31-15 victory over the Bears at Chicago on Monday night — different from the rest. When Harris entered the contest, the Saints (6-8) were in a scoreless tie instead of trailing by anywhere from four to 17 points against opponents the entire New Orleans team struggled against.

That Harris delivered perhaps the best performance of his career has something to do with the fact that the Bears were so inept they benched veteran quarterback Jay Cutler two days later. But it also helped that Harris was pressed into duty when the Saints had their entire offensive playbook at their disposal and not limited in what they could do because of a deficit.

That was not the case six days earlier, when Harris went into a game that the Saints were losing 17-0 at home and ultimately dropped a 41-10 decision to Carolina.

“I think a lot has to do with, when I get in the game, what’s the situation?” Harris said immediately following the win against the Bears (5-9). “It was a close game (in Chicago), so we could mix the run and the pass if we wanted to.”

Saints coach Sean Payton added, “Obviously, if you’re a tackle in (the NFL), you want to enter a game with a lead.”

Harris arrived in New Orleans as an undrafted rookie in 2012, but he missed most of his first year hurt and has only started in two games in his career, both at right tackle in place of an injured Zach Strief.

This year the Saints have turned to Harris more than usual, even if he hadn’t registered a start. He’s already logged a career-high 257 offensive snaps with two games left this season, and 218 have come in three contests left tackle Terron Armstead was ruled out of early as well as one that Strief had to leave hurt.

Playing between 73 and 86 percent of the offense’s snaps in those outings, in games the Saints lost, Harris had difficulties like most of his teammates did.

In a game Harris came into because Armstead had a concussion when the Saints were down 7-0 in Dallas on Sept. 28, he seemed to be among the reasons New Orleans permitted a significant amount of pressure against what was primarily a four-man rush. The Cowboys triumphed 38-17 that night.

Against Cincinnati on Nov. 16, after Strief was concussed in the first quarter, Harris surrendered three of the 10 quarterback pressures the Bengals posted. But Harris was far from the only vulnerability in a 27-10 Saints loss.

The toughest circumstances Harris walked into was subbing in for Armstead 15 snaps into the Saints’ 31-point loss at home to Carolina on Dec. 7 after the starting left tackle hurt his neck. Harris allowed a half-dozen hurries and a sack, but he earned praise from Payton for fighting through an ankle injury knowing nobody under him on the team’s depth chart was active.

The most friendly conditions Harris had coming in as an emergency replacement was in Chicago. And the positive effect on Harris was palpable. After Armstead went out with a hurt neck again and Harris marched in, Saints quarterback Drew Brees wasn’t subjected to much pressure despite being sacked twice, and he threw for 375 yards and three touchdowns while New Orleans punched in a rushing score.

Harris’ Bears game was his cleanest of the four he saw lots of action in this year, prompting Brees to later say of the young tackle, “I don’t think twice when Bryce is in there.”

There’s no denying Chicago’s defense was ranked 30th in the NFL as of Thursday. But in terms of his self-belief, Harris encountered them at a perfect time.

Armstead was listed on Wednesday’s injury report and missed Thursday’s practice because of his neck issue. If Harris is needed when the Saints host Atlanta (5-9) on Sunday, he’d be operating against the league’s worst-ranked defense.

As Harris said about his clash against the Bears, “It was a good performance after my (Carolina) performance. It helped me boost confidence that way.”