SAN FRANCISCO (CBS SF) — Buster Posey, one of the greatest catchers of his generation and the greatest catcher in San Francisco Giants history, will announce his retirement Thursday, according to The Athletic’s Andrew Baggarly.

While neither Posey nor the Giants have commented, the San Francisco Chronicle and the Associated Press also said sources had confirmed the Giants star’s stunning announcement.

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After undergoing hip surgery and opting to sit out the COVID-shortened 2020 season, the 34-year-old Posey enjoyed a resurgent 2021 season, hitting .304/.390/.499 with 18 home runs in 454 plate appearances. It was his best year since his peak years in the early-2010s.

Posey caught five of the final six regular-season games and 10 of the last 13 as San Francisco clinched the division on the final day.

The Giants said last month that they would exercise Posey’s $22 million club option for the 2022 season as long as the veteran catcher wanted to keep playing after a stellar year.

“He is in our estimation the best catcher in baseball this year,” Farhan Zaidi, Giants president of baseball operations, said when discussing the option two weeks ago. “… Obviously want to have conversations with Buster and continue to have internal conversations about that but having him on this team next year is a high priority.”

Posey formed the veteran core along with Evan Longoria, Brandon Crawford and Brandon Belt for a club that won a franchise-record 107 games and the National West regular-season crown before losing to the Los Angeles Dodgers 3-2 in the NL Divisional Series.

The seven-time All-Star catcher helped led the Giants to World Series titles in 2010, 2012 and 2014. He was the 2010 NL Rookie of the Year and the 2012 NL MVP, while also earning four Silver Slugger Awards, one Gold Glove Award behind the plate, and one NL batting title.

Baseball historian and radio host Marty Lurie said the rings make Posey the best catcher in Giants franchise history, describing him as the coach on the field who caught the trio of Giants pitching greats in Matt Cain, Tim Lincecum and Madison Bumgarner.

“His resiliency, and just seeing him behind the plate and seeing his whole career, that to me is what I will always remember about him,” Lurie told KPIX 5.

Posey though suffered two season ending injuries in his career and took several knocks to the head behind the plate.

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Lurie said he could tell the injuries were taking a toll. “The grind got to him and I think he really would like to live a normal so-called life and I think that’s the bottom line of it,” he said.

Word of the announcement triggered an avalanche of reaction on social media.

Giants fan Shahbano Khan posted: “I’m in tears. Tomorrow is going to be tough. He is the epitome of not only an exceptional baseball player but a human being too. So grateful for everything he’s given to the Giants, the fan base, the community, & the baseball world as a whole. Happy retirement”

Scotty Joe Walton added: “I hope he changes his mind. If he doesn’t, he’s a shoe in HALL OF FAMER and one of the greatest GIANTS to ever wear the uniform. I’m gonna miss him!!!”

Brit joined in: “Thank You Sir, for being one of the greats! For making it easy to cheer for, tho I’m not a Giants fan. Thank You for playing the game right with the best attitude.Happy Retirement @BusterPosey I among many will miss following your stats & fighting over you during fantasy draft.”

Even Dodger fan Dodgers fan Kimmie had some kind words — “Dodgers fan til the day I die but @BusterPosey is a classy dude and arguably one of the most efficient and talented catchers in the game. Happy Retirement, dude!”

Outside Oracle Park on Wednesday night, fans were in disbelief.

“If there is a chance he can change his mind, I hope he does,” Steve Johnson said.

Brian Davis added, “I can see from his perspective how it made sense, this is the time. But of course we want him to play forever.”

Giants fan Eileen Ahn expressed gratitude for Posey’s legendary career. “Buster, thank you so much. You have made me, as a Giants fan, so happy over the years and being able to hold in, even though we had some tough times. Best of luck to you and all you have done for us,” Ahn told KPIX 5.

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Andrea Nakano contributed to this report.