Trent Grisham of the Padres hopes his team’s consistent faith continues in the NLDS.

It’s a common refrain as September turns to October and playoff-bound major leaguers transition from regular-season to postseason mode: “You can’t just turn it on this time of year.”

Unless you’re Trent Grisham, who must have missed that memo.

The San Diego Padres center fielder had a brutal end to an awful regular season, batting .107 with a .345 on-base-plus-slugging percentage, one homer and four RBIs in September and early October to cap a year in which he hit .184 with a .626 OPS, 17 homers and 53 RBIs.

The left-handed-hitting Grisham struggled so much down the stretch that he started only six times in 15 games before the Padres clinched a playoff spot Oct. 3, yielding the bulk of the playing time in center field to rookie Jose Azocar. Grisham reached base only eight times in his final 55 plate appearances.

Then Grisham stepped onto the postseason stage under the bright lights of New York City and morphed into Ken Griffey Jr., batting .500 (four for eight) with two homers and three RBIs and walking twice to help the Padres beat the Mets in a three-game National League wild-card series in Citi Field.

“I don’t know,” Grisham said after Monday afternoon’s workout at Dodger Stadium ahead of Tuesday night’s NL Division Series opener against the Dodgers. “Just felt good up there. I kind of felt good going into the last week of the season, and kind of just carried it over.”

Grisham reached base eight times in 12 plate appearances against the Mets. He hit a solo homer in each of the first two games, Friday’s 7-1 Game 1 win and Saturday’s 7-3 Game 2 loss. He had two hits — an RBI single in the fourth inning and a single in a two-run eighth — in Sunday’s clinching 6-0 win.

He also made one of the best defensive plays of the series, racing 95 feet into the right-center-field gap to make a lunging catch of Mark Canha’s drive to the wall with a runner aboard in the bottom of the fifth to preserve a 4-0 lead, a play that had a catch probability of 25%, according to Statcast.

“I’ve never seen that — a guy go from A to Z when the intensity was ratcheted up a hundredfold,” Padres manager Bob Melvin told the San Diego Union-Tribune after Sunday night’s game.

“You have to really, really understand how much character is involved in something like that. Beat down going into the series and ends up being basically the MVP. I’ve never seen anything like that.”

Grisham’s breakout performance at the bottom of the order will earn him a more prominent role in the best-of-five series against the Dodgers, who have three left-handers — Julio Urías, Clayton Kershaw and Tyler Anderson — in their rotation.

The Mets started three right-handers — Max Scherzer, Jacob deGrom and Chris Bassitt — in the wild-card round. Asked whether he expects Grisham to be in the lineup against Urías in Game 1 on Tuesday night and Kershaw in Game 2 on Wednesday night, Melvin said, “I do.”

The manager added: “He has had a history of hitting lefties. Actually, some years better. It’s just all about how the quality of his at-bats are and what he means to us. Even if production-wise his offense was down a little, he still makes up for it on the defensive end and on the baserunning end as well.”

Grisham has a career .237 batting average, .732 OPS, 13 homers and 46 RBIs in 325 at-bats against left-handers and a .217 batting average, .704 OPS, 35 homers and 119 RBIs in 959 at-bats against right-handers.

He didn’t hit left-handers or right-handers very well this season, but even when he got benched in September, Grisham never felt like Melvin, in his 19th year as a big league manager and first with the Padres, lost confidence in him.

“Consistent faith,” Grisham said of the impact Melvin has had on him. “He has believed in me since day one. He told me throughout the entire year when I was struggling, when I was down, and he told me [Sunday] night after winning that series. That consistency speaks volumes to me. I really appreciate that.”

Melvin praised Grisham for his perseverance.

“You have to give him a lot of credit for going through a very difficult season, getting benched for a while, coming to the [wild-card] series and looking like an All-Star offensively, defensively, running the bases,” Melvin said. “It takes some mettle to fight through something like that and have the type of series he did.”

Beware of the underdog

The Dodgers had a franchise-best 111-51 record and finished 22 games ahead of the second-place Padres (89-73) this season, but while the Dodgers were playing intrasquad games at Chavez Ravine over the weekend, the Padres were building a head of steam in New York against the Mets.

Which could make the Padres even more dangerous in a short series, as Dodgers first baseman Freddie Freeman knows all too well.

Freeman was a star on an 88-win Atlanta team that had the worst record of 10 playoff teams before running the table last October, beating Milwaukee in the NL Division Series, the Dodgers in the NL Championship Series and the Houston Astros in the World Series.

“No one picked us to win anything last year, so really there’s no pressure,” Freeman said of the 2021 Braves. “You just have to play the game. I think when you have that mentality, you have nothing to lose, and everyone just talks about the other team, so it’s kind of easy to go out there and just play your game.

“I don’t think anybody in this room picked the Padres to beat the Mets. They’re playing good baseball. They’ve been playing good baseball to get there. We know they’ve got a lot of momentum coming off of that. We’ve got to go out there and strike first.”

Looking for redemption

The Dodgers should be heavily favored to win Game 1 against Padres right-hander Mike Clevinger, the No. 4 starter who went 0-2 with a 9.69 ERA in three starts against the Dodgers this season, giving up 14 earned runs and 16 hits, including five homers, in 13 innings.

Clevinger’s only playoff start against the Dodgers was also painful — he walked three and struck out one in a scoreless first inning of a 5-1 loss in the 2020 NLDS opener. Clevinger departed because of an elbow injury, underwent Tommy John surgery that November and missed the 2021 season.

“We tried to almost tape my arm together to get me out there, and it just didn’t last,” Clevinger said Monday. “We knew going into it that I had a torn [ulnar collateral ligament]. I opted to pitch. It was almost like, ‘How can we figure out a way to pitch?’

“So it will be good to go out there with a fresh and healthy arm.”