Even before he became a World Series icon, Madison Bumgarner admired those who shouldered an extra workload in October.

So after the Giants won it all in 2012, the left-hander helped throw a party for his kind of postseason heroes.

He hosted a lunch for the groundskeepers.

“They take care of the field for us,” Bumgarner explained this spring.

“You leave the park late, and you can see the lights in the stadium are still on till midnight. They put in a lot of work and a lot of time and don’t usually get recognized for it.”

Bumgarner famously toiled overtime to deliver another celebration last year. In a postseason for the ages, he went 4-1 with a 1.03 ERA and capped things off with a World Series flourish. On two days of rest after winning Games 1 and 5 as a starter, he came out of the bullpen to throw five shutout innings against the Kansas City Royals in Game 7.

Before that, Bumgarner was a midlevel star whose regular-season ERA ranked 21st in the majors.

After that, he was the Sports Illustrated Sportsman of the Year, had the No. 1 selling jersey according to Fanatics.com and went on the “Tonight Show” to hand Jimmy Fallon a pair of “MadBum” boxer shots. (“A normal thing for a guy to give another guy on TV,” Bumgarner drawled as he made the exchange.)

Has MadBum gone Hollywood? Hardly.

Bumgarner, 25, is handling his newfound fame as if he’d defeated the Royals with a rake and shovel. He turned down most of the endorsement opportunities that came his way but made a rare exception for the Carhartt clothing company. The appeal is that he wore that brand growing up on his family farm in northwestern North Carolina.

“Yeah, I’ve been wearing those clothes all my life. So that was a pretty cool thing for me and my family to get to be a part of,” he said. “It’s more of a blue-collar type thing. Carhartt is about working with your hands. They make work clothes — stuff that you can really work in.”

It was also Bumgarner’s kind of fashion statement. He didn’t own a suit until he attended the Sportsman of the Year banquet. The magazine noted that when he married to his high school sweetheart, Ali, he did so in a white open-collar shirt and blue jeans while carrying a pocketknife.

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Bumgarner’s national television ad for Carhartt will begin airing near opening day. Expect grits, not glamour. The camera crew’s goal was to capture a day in the life of Bumgarner’s ranch, a 116-acre farm in Lenoir (pop. 18,042) with 20 horses, 60 cattle and no shortage of chores.

Building his brand? In Bumgarner’s case, that involves a branding iron in hand.

“What he does in an average workday on his ranch is pretty incredible,” said Tony Ambroza, the senior vice president of marketing for Carhartt. “People who follow him will quickly realize why he’s so tough. And what makes him as strong as he is. He epitomizes a simple thing we believe in: Before there were workouts, there was work.”

The ad was directed by actor Jason Momoa, best known for playing Khal Drogo on HBO’s “Game of Thrones.” In the series, Momoa played a tall, powerful, fearsomely bearded warrior. So, yes, he and Bumgarner got along famously. A photo of the two chugging beers side-by-side set social media ablaze in February.

Momoa spent much of his early life in Iowa, so he knew his way around a farm. Bumgarner said he loved working with someone who understood and respected the land.

“For sure,” the pitcher said. “Obviously, he did his thing (as the director), but I didn’t feel much need to change anything.”

Carhartt was founded in 1889, when it specialized in bib overalls for railroad workers. Now, the company markets to search-and-rescue crews, firefighters, electrical workers — and major league groundskeepers.

That’s how Bumgarner connected with the company in the first place. When he hosted the lunch for the Giants crew early in 2013, the pitcher arranged for the groundskeepers to get a full set of gear from the company — jacket, hat, pants, shirt and a T-shirt.

“He stood up and said, ‘I just want to thank you for all your hard work and for helping me to get to where I’m at,'” recalled Greg Elliott, the Giants director of field operations. “He’s a humble guy, and it doesn’t surprise me that he’s playing it down. But that was a big moment for me and my crew.”

That party for the groundskeepers featured workman’s fare (a barbecue), but at a glitzy locale (a yacht club). Bumgarner has a knack for country-frying anything he touches. As part of his whirlwind offseason, he made a trip to Las Vegas — for the National Finals Rodeo. He later indulged a photo shoot for the cover of the Giants Magazine — while next to an ox and dressed like Paul Bunyan.

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Bunyan, like Bumgarner, grew legendary for overpowering lots of lumber. But Bunyan was never on a tree count. In contrast, Bumgarner faced endless questions all spring about how his body would hold up after his epic workload of a year ago.

He totaled 270 innings, the most by a Giant since Ron Bryant reached that same total in 1973. Bumgarner’s count included a record 52.2 innings in the postseason. It was the heaviest workload for a pitcher 25 or younger since 2000, according to ESPN.

So people keep asking the 6-foot-5, 235-pound part-time ranch hand whether he feels OK. Because he can’t outright laugh, Bumgarner takes the next best route and defuses the questions with wry comebacks.

How does your arm feel?

“Feels just like an arm. It’s the craziest thing.”

What about the high-stress innings?

“High stress for you?”

Your World Series MVP raised expectations.

“Did it? … It didn’t change mine from what they were.”

Even manager Bruce Bochy got in on the act, deadpanning that Bumgarner would be his opening day starter before adding, “Oh, he’s going the second game, too.”

Bumgarner threw 4,074 pitches last season but appeared to get stronger as he went along. Batters hit just .153 against him during the postseason, when he struck out 45 and walked six.

His track record speaks to his durability. Bumgarner has four consecutive seasons with at least 31 starts and 200 innings.

The Giants don’t doubt his resilience, not even those just getting to know him. Nori Aoki, who played for the Royals last season, joked upon signing with the Giants during the offseason that he wanted a wrestling match with Bumgarner. He backed out, of course, almost the second he arrived. “He was little bigger than I expected,” Aoki said.

Through his interpreter, he added that weapons should be allowed in any match against someone of Bumgarner’s size.

Bumgarner grew up learning that brute force was his best option on the diamond. Kevin Bumgarner, concerned about his son’s long-term future, didn’t let Madison throw curveballs until he was 16.

“Probably longer than that, actually,” Madison Bumgarner says now. “It’s just what we were taught back then — that breaking balls are bad for your arm. Don’t throw them. So I didn’t.

“We didn’t have any scientific research behind that, but that’s what I was taught. It was better for you. I don’t know if it’s right or wrong or if they even know yet.”

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Last year, Bumgarner’s fastball averaged a career-best 92.1 mph during the regular season, according to FanGraphs.com. And his repertoire has broadened since those days at South Caldwell High. He threw his fastball 43.5 percent of the time last season, according to FanGraphs, complementing it with a slider (34.9 percent of the time), curveball (14.0) and change-up (7.5).

In the wake of his postseason success, it’s common to debate where Bumgarner is headed in 2015. John Smoltz, another one-time October ace, ventured recently on the MLB Network that the Giants’ left-hander is poised for a new level of regular-season stardom.

“He’s going to find that he gets better because something clicked during the postseason,” Smoltz said on the air. “I think there’s a point in a pitcher’s career when you say, ‘Ha! I got it!’ I think we’re going to see a lot more consistency.”

Co-host Brian Kenney countered that Bumgarner ranks somewhere below greatness if you look beyond the champagne to the pitcher’s regular-season record. The left-hander’s ERA-plus — that is, adjusted by ballpark — ranks a mere 32nd in the majors over the past three seasons. He ranks 24th in terms of wins above replacement (WAR) during that span.

“He didn’t make my top 10,” Kenney said. “That sounds crazy, but he’s more of a 15 to 25 guy during the regular season.”

Bumgarner, of course, has zero interested in the fuss. Though immune to high pitch counts, he tires quickly of questions. People keep wanting to know about his “different” offseason.

He’s just ready to saddle up and ride.

“It hasn’t been different for me. Maybe it’s been different for other people,” Bumgarner said. “But I’ve stayed the same and haven’t changed anything.

“There have been a lot of doors that opened because of the postseason, I guess, and a lot of friendships made. It’s been a blessing for me. It’s stuff that I never thought would have happened — or should have happened — and it’s been a lot of fun.

“But I know, and everybody else knows, that you can’t let it change who you are.”