SAN FRANCISCO — One year after the Giants got rid of their manager, they fired the man who hired him.

The Giants on Monday parted ways with president of baseball operations Farhan Zaidi, who was hired in 2018 to overhaul the organization but reached the playoffs only once in six seasons. The decision brings an end to a polarizing regime that put together the winningest team in franchise history but never won over large segments of the fan base and couldn’t figure out a way to consistently win at Oracle Park.

In a surprise, former catcher Buster Posey, who previously had bought into the Giants’ ownership group, was named the new president of baseball operations.

“We are looking for someone who can define, direct and lead this franchise’s baseball philosophy, and we feel that Buster is the perfect fit,” Giants chairman Greg Johnson said in a statement released by the team. “Buster has the demeanor, intelligence and drive to do this job, and we are confident that he and Bob Melvin will work together to bring back winning baseball to San Francisco.”

When Posey returned to the Giants to assume an ownership role, there was an expectation that he could do as much as he was willing to take on with four young children. Posey’s selection comes as a surprise only because of how important the daily duties of fatherhood are to him, but the Giants likely will hire additional baseball operations personnel to handle day-to-day tasks.

As Johnson stated, Posey will define the direction of the organization, which will please not only the fan base but a frustrated clubhouse. The announcement of the change referred to “open positions” within the organization.

“I’m very excited for Buster and excited to see what he brings in this new position,” Giants ace Logan Webb, who played with Posey in 2019 and 2021, told NBC Sports Bay Area. “Buster is a brilliant baseball mind, and I can’t wait to be a part of it.”

The new direction is about as far away as one can get from the previous regime.

The Giants hired Zaidi away from the Los Angeles Dodgers after they lost 187 total games in 2017 and 2018 and fired general manager Bobby Evans, and initially, the move was met with just about universal praise within the industry. Zaidi came with a strong reputation from helping to build the Oakland Athletics and the Dodgers, and he arrived with the promise of rejuvenating an organization that seemingly had fallen behind the times.

Zaidi’s first season was a tricky one to maneuver, as he worked behind the scenes to make changes to baseball operations and analytics while also allowing manager Bruce Bochy to properly say goodbye. After that first season, he hand-picked Gabe Kapler to be his manager, and while the initial press conference was awkward and borderline contentious, the Giants soon were back in the playoffs. They won a franchise-record 107 games in 2021, with Kapler being named NL Manager of the Year and Zaidi seemingly hitting the jackpot with every move.

The heavy use of openers and platoons was jarring to fans, but it also was initially successful. Zaidi is known for unearthing diamonds in the rough, and he hit on players such as Mike Yastrzemski, LaMonte Wade Jr. and Thairo Estrada, all of whom came to San Francisco essentially for free. The Giants continued to strike out on marquee free agents, but for a while at least, it seemed that might not matter.

Everything changed after Posey retired, and looking back, members of that 2021 team talk often of just how much of the heavy lifting was done by him, Brandon Crawford and Brandon Belt. Zaidi never was able to rebuild that core nor even come close.

Back-to-back mediocre seasons forced Zaidi to fire Kapler, a close friend, and completely change course. He went to the opposite end of the spectrum in hiring Melvin and attempted to go big in free agency, but the Giants missed the playoffs for the third consecutive season.

Zaidi ultimately was ousted for failures in two key areas. He couldn’t build a strong player development system, with some notable misses in the first round of the draft. While 2023 first-round pick Bryce Eldridge looks like a future star, only one of Zaidi’s previous four first-rounders has reached the big leagues.

The Giants generally are viewed as having a bottom-half farm system, and the best young player on their roster — Heliot Ramos — was drafted by the previous regime and only broke through after injuries opened the necessary playing time this year.

Zaidi repeatedly came up short at the top of the free agent market, and expensive winters the past two years did not pan out. The 2022-23 offseason proved to be a disaster, with Mitch Haniger and Ross Stripling traded, Sean Manaea opting out and Michael Conforto not living up to expectations. The Giants pushed payroll into the tax this past offseason, but some bad luck led to poor results.

Jung Hoo Lee suffered a season-ending shoulder injury, and Blake Snell had a rough first half after signing late in the spring. Jorge Soler was dumped on the Braves after just four months so the Giants could get out from under the remainder of his contract. The offseason looked strong on paper, and Matt Chapman and Snell ultimately lived up to expectations, but it wasn’t enough to get the Giants over the hump.

The Giants had only about a 10 percent chance of making the playoffs at the July 30 trade deadline, but Zaidi held his best chips and made one last push. It didn’t work, and in recent weeks, the temperature was turned up.

The Giants finally made a decision. After more than two decades of being run by Brian Sabean and his group, they now will turn baseball operations over to Posey.