Garrett Broshuis toiled for six seasons as a Giants minor league pitcher, never getting to live his dream of stepping on the mound in San Francisco. His final record after 150 games is sigh-worthy: 54 wins, 55 losses.

Despite that unremarkable career, thousands of current and former minor league players, as well as executives from all 30 big league clubs and the league bigwigs in New York, know exactly who Broshuis is.

The players owe him a debt. The executives no doubt wish he would have become a big league pitcher — and not a lawyer who threatens them in court.

After realizing that he would not get to take that final step to pitching in the majors, Broshuis quickly pivoted from baseball to law school. He’s now the lead attorney in a lawsuit that aims to force major league organizations to follow federal and state wage laws and pay minor league prospects at least the minimum they would earn slinging fries at a fast-food joint.

According to Major League Baseball, the monthly minimum salary for minor leaguers is as low as $1,100 in rookie and Class A ball, jumping to $1,500 in Double-A and $2,150 in Triple-A, well below the minimum wage when factoring their time commitment over the five months a year they are paid.

The monthly minimum salary in the majors is about $90,000, with an annual average of $4.3 million.

The lawsuit seeks to upend a system that has been in place since the 1800s. It has gone unchallenged under the notion of “that’s the way it’s always been,” and also because Major League Baseball has been able to operate however it chooses under a unique exemption from federal antitrust laws that Congress passed in 1922.

Broshuis’ lawsuit skirts the antitrust issue largely by arguing that the minor league pay system violates state wage laws.

Broshuis, who starred at the University of Missouri before the Giants selected him in the fifth round of the 2004 amateur draft, sees this suit as a greater calling than throwing a baseball over the plate.

The action has lingered without a trial date for five years, although one could be set soon after a series of appellate victories for Broshuis. One more year, and the lawsuit will have lasted as long as his professional pitching career, which ended in 2009 after Giants officials told him he no longer was considered a prospect.

“It was definitely in some ways heartbreaking,” Broshuis said by phone last month from his St. Louis office. “It’s a failure, but at the same time it’s a beautiful failure because you put everything you had into it, and there are beautiful things to do if you come up short.”

Broshuis and his firm, Korein Tillery, filed the suit before the issue of minor league pay became as visible as it is now. The cause even seeped into the presidential campaign last month when Democratic candidate Bernie Sanders invited Broshuis onto the stump to talk about it.

The suit, filed in U.S. District Court in San Francisco, has expanded from three named plaintiffs, including onetime Giants pitching prospect Oliver Odle, to 45. More significant, the court has certified the suit as a class action that Broshuis estimates could cover as many as 10,000 players.

The defendants are Major League Baseball and 22 of the 30 franchises, including the Giants and A’s. Eight teams were excluded over jurisdictional issues.

The suit seeks untold millions of dollars in back pay, compliance with wage laws and the end to a compensation system as entrenched as “three strikes and you’re out.”

MLB counters that hourly wage laws were not meant to cover athletes who play games and take trips with no set hours, and spend much of their own time working out at gyms, batting cages and bullpen mounds to gain a competitive advantage over teammates in a race to reach the majors.

The league and its teams also say they spend considerable sums to train players and provide medical care when they are hurt.

A spokesman for Major League Baseball said the league would not comment for this story, but pointed toward an interview that Commissioner Rob Manfred gave to the Toronto Sun in October.

“We’re not opposed to paying minor league players any particular wage,” Manfred said. “What we are opposed to is the administrative requirements of keeping track of hours and overtime. They’re simply impractical in minor league baseball.”

In July, a Ninth Circuit appellate panel in San Francisco gave Broshuis and his clients a big victory, allowing them to expand the suit as a class action to cover players who spent spring training in Arizona and Florida — practically all of them — and not just those who played minor-league ball in California.

Major League Baseball has not been able to kill a lawsuit that was viewed as nothing more than a nuisance when it was filed.

“I don’t see this is as something quixotic,” Broshuis said. “It has real grounding in the law.”

Broshuis, now 38 and a father of three, had seen the end of his baseball career coming. He studied for his law school admission test on long overnight bus rides in the minors as his teammates slept.

After his final game in 2009 he took the two classes he needed to complete a psychology degree at Missouri — graduate-level psychology and Spanish poetry — and by 2013 had a law degree after graduating summa cum laude from the St. Louis University School of Law, where he was valedictorian, Phi Beta Kappa and editor in chief of the law journal.

Not bad for a small-town kid. Broshuis grew up in Advance, Mo., population 1,200. (“We have a McDonald’s now, which was controversial when it came in.”)

Broshuis said his pivot to law partly resulted from the financial hardships many of his teammates encountered, especially those who had not gotten big bonuses like the $160,000 the Giants paid him when they drafted him as a blue-chip prospect.

Broshuis’ wife of 13 years, Alicia, ran track at Missouri and knew how much athletes must train in their offseasons to stay competitive. She could not believe that minor leaguers are not paid over the winter, nor at spring training.

During the season, Alicia stayed home in St. Louis and worked three gigs as a physical therapist to make ends meet. In the winter, Garrett gave private pitching lessons and worked in a university psych lab.

“Definitely, this was an ongoing grind,” Alicia said. “He’s a thinker. He’s the type of person, when he sees inefficiencies and inequality in an area, he thinks about it a lot. He talked about it with teammates and me. He said, ‘This isn’t right. They know they have the money to pay us more to at least ensure we have adequate food and housing through the year.’”

Garrett could not shake the memory of a conversation with one Latin American roommate at Double-A Connecticut.

Broshuis noticed his teammate would not eat until he got to the ballpark in the early afternoon — a peanut butter and jelly sandwich supplied by the team.

Broshuis finally asked why, and the teammate responded that he could not afford food. He was deep in credit-card debt, had no family to help him and did not get a big signing bonus.

“The guy was a great ballplayer,” Broshuis said. “Imagine how good he could have been if he could have afforded Chipotle for lunch.”

Minor leaguers must pay for their own housing, and stories abound of players crammed into small apartments and sleeping on air mattresses to save money. They sometimes live with host families, as Broshuis did at several stops.

“I’m indebted to them to this day,” Broshuis said. “But why are we asking random people in the community to take in players in an industry making $10.7 billion?”

Neither Broshuis’ path nor the lawsuit surprised Trevor Wilson, the onetime Giants pitcher who coached Broshuis in 2005 on a Class A San Jose team that won the California League championship.

“Very smart, maybe the smartest guy in the locker room, including the staff,” Wilson said by phone from his Oregon home.

“That’s who he was. He was a take-charge guy. We knew right away he was very educated and very mature. ... It doesn’t surprise me what he’s doing, and it’s very admirable, to be a pioneer in this.”

Alicia Broshuis called her husband a “doer.”

“It’s really easy for a person to work hard for one day,” she said, “but he puts in this meticulous work, day after day, chipping away at things. That’s pretty much what he did in his six years in the minor leagues, three years in a law school and now a practicing attorney, chipping away at an issue that means so much to him, so much to us, because we lived it.”

The lawsuit and attendant publicity have helped goose action from all sides.

In March, the Toronto Blue Jays said they would raise minor league pay by 50%.

In 2018, with the issue becoming more public, Major League Baseball spent more than $1 million in a successful lobbying effort that got Congress to pass the Save America’s Pastime Act.

The law, tucked into an appropriations bill that President Trump signed, directs teams to pay minor leaguers the minimum wage, but only for 40 hours, and without overtime, no matter how much they work.

An MLB proposal, proffered in negotiations with the organization that runs minor league baseball, calls for a significant increase in pay for minor league players and improvement in their working conditions, but lops off 42 of the 160 affiliated teams, which would vastly reduce the number of prospects the big league clubs have to pay.

“I hope it’s just an opening proposal to move the ball,” Broshuis said. “There’s certainly enough money in the game to increase minor league wages above the poverty line without cutting 25 teams. We can figure out a way do that without cutting 1,000 minor league jobs and other associated jobs.

“When MLB says it really needs to increase minor league salaries, I hope they are being sincere. For five years that’s what we’ve been saying, and they’ve fought us in court and they’ve fought us in Congress.”

After five years, the court fight will not begin in earnest until a trial date is set. Broshuis hopes to see that this year after a Ninth Circuit ruling on Friday that largely leaves the defendants no option to kill the suit aside from a successful appeal to the U.S. Supreme Court.

Henry Schulman is a San Francisco Chronicle staff writer. Email: hschulman@sfchronicle.com Twitter: @hankschulman