The baseball world was shocked Wednesday with news that Buster Posey intends to retire after 12 seasons in the Major Leagues. While the decision certainly came as a surprise, Posey is not the first player to abruptly walk away from the game.

With that in mind, here's a look at other unexpected retirements in big league history. It's an interesting mix of respected regulars, occasional All-Stars, and some of the game's all-time greats:

Buster Posey
Posey officially announced his retirement the day after news broke that he was calling it a career.

The 34-year-old catcher was coming off a resurgent season at the plate, in which he showed he had much more left in the tank by hitting .304/.390/.499 with 18 home runs in 113 games for the Giants. He opted out of the pandemic-shortened 2020 campaign the prior year and returned rejuvenated, helping San Francisco win a franchise-record 107 games and the National League West for the first time since 2012.

The Giants drafted Posey fifth overall in 2008 out of Florida State University, and he made his MLB debut on Sept. 11, 2009. He won the NL Rookie of the Year Award in 2010, his first full season in the Majors. That year, he also helped guide the franchise to its first World Series title since moving to San Francisco in 1958.

In 2011, Posey suffered a catastrophic leg injury that led to the establishment of the rule against catchers blocking the plate and not allowing a lane for the baserunner. Posey returned to action in 2012 and went on to win the NL MVP Award after posting a .957 OPS (171 OPS+) with 24 home runs and 103 RBIs. He led the Giants back to the World Series, where San Francisco swept the Tigers for its second championship in three years.

Two years later, Posey helped the Giants win their third World Series title in five years with a seven-game victory in the Fall Classic over the Royals. Overall, he hit .252/.321/.345 with five home runs in 58 career postseason games, setting the franchise record for postseason hits with his 54th during the 2021 NL Division Series against the Dodgers.

Posey caught three no-hitters during his career -- a perfect game thrown by Matt Cain in 2012, and no-hitters thrown by Tim Lincecum in 2013 and '14. In addition to his Rookie of the Year and MVP Awards, Posey was a seven-time All-Star, four-time Silver Slugger Award winner and won a Gold Glove Award in 2016. Overall, he played in 1,371 games and hit .302/.372/.460 with 158 home runs and 44.9 WAR (Baseball Reference).

Adam LaRoche
LaRoche stunned the White Sox and the baseball world by announcing his retirement during Spring Training in 2016. The 36-year-old first baseman had recently had a disagreement with executive vice president Ken Williams over the presence of LaRoche's son, Drake, with the club.

LaRoche played 12 Major League seasons, making his MLB debut with the Braves in 2004, and spending the first three seasons of his big-league career with Atlanta before being traded to the Pirates. Following two solid seasons with Pittsburgh and brief stints with the Red Sox and again with the Braves, he signed a free-agent contract with the D-backs in 2010.

Following one season with Arizona, LaRoche signed as a free agent with the Nationals, for whom he played from 2011-14. He signed with the White Sox prior to the '15 campaign. Overall, he hit .260/.336/.462 with 255 home runs in 1,605 games.

Michael Cuddyer
Cuddyer stunned the Mets in December when he unexpectedly announced he would retire at age 36, halfway through his two-year, $21 million contract. Cuddyer was dogged by injuries in the final seasons of his 15-year career, and he made his decision to retire shortly after undergoing surgery in November to repair a core muscle injury.

"I just knew I wasn't going to be able to give what I expect myself to give out on the field," Cuddyer told reporters. "I knew I could still bring leadership, and still bring qualities that can contribute. But I take a lot of pride in playing the game the right way, and playing the game the way that I know I was capable of playing. I didn't feel like I could bring that anymore. And with great humility, I made the decision."

Ken Griffey Jr.
Griffey shocked the baseball world when he suddenly retired at age 40 on June 2, 2010, during his second stint with the Mariners.

A 13-time All-Star with 630 career home runs, Griffey was batting .184 with no homers and seven RBIs when he announced his retirement in a statement released through the Mariners. Afterward, the future Hall of Famer got in his car and drove home to Orlando, Fla., in a bizarre end to a 22-year career.

Griffey said to The Seattle Times that he previously had told Mariners management "that if I become a distraction or feel that I would be a distraction, then I would retire, because that's the one thing that I didn't want."

Gil Meche
Meche walked away from the $12 million remaining on his contract with the Royals when he retired in January 2011 following a 10-year career as a starting pitcher. For Meche, the decision was not about finances but rather his doubts that his cranky right-shoulder would hold up through another season.

"A lot of people might think I'm crazy for not trying to play and make this amount of money," Meche told reporters, "[but] I don't think I'm going to regret it."  

Mark McGwire
McGwire hinted at retirement after the Cardinals were eliminated from the 2001 postseason, telling reporters, "It comes down to what I can do physically. My body is pretty worn out. And my mind is definitely worn out."

A few weeks later on a Sunday night in November, McGwire faxed his letter of resignation to Rich Eisen of ESPN, who broke the news on SportsCenter.

McGwire was 38 at the time of his retirement and walked away from a two-year, $30 million extension with the Cardinals. The slugger ended his 16-year career with 583 homers.

Mike Schmidt
Schmidt stunned those closest to him when he retired at age 39 on May 28, 1989, midway through a West Coast road trip with the Phillies. The future Hall of Famer was mired in a slump and had been contemplating retirement, when suddenly an omen appeared.

Schmidt booted a routine grounder in a tie game against the Giants, and the next batter hit a grand slam.

"Mentally, I had sort of been thinking about it," Schmidt recalled to the Philadelphia Inquirer. "'Might this be the end? What other sign do I need?' I was looking for a jumping-off point. ... After the game, I walked into the clubhouse and it was like I was in a fog. I showered real fast, paid the clubhouse guy and went out and sat on the bus all by myself for 30 or 40 minutes to contemplate my next move."

Sandy Koufax
Koufax made a surprise announcement about his retirement at age 30 on Nov. 18, 1966, following another stellar season with the Dodgers that saw him win the National League Cy Young Award for the third time in four seasons and help his team reach the World Series.

Koufax's decision to hang up his spikes came as a result of chronic arthritis in his pitching arm that he felt could be further damaged by continuing to pitch. Following his retirement, Koufax became the youngest player ever to be inducted into the Hall of Fame at age 36.

Lou Gehrig
In perhaps the most well-known speech in North American sports history, Gehrig announced his retirement before a packed house at Yankee Stadium on July 4, 1939.

The Yankees were honoring Gehrig between games of a doubleheader against the Washington Senators, only two months after the future Hall of Famer found out he had been diagnosed with amyotrophic lateral sclerosis (ALS).

Following a lengthy ceremony featuring numerous gifts and speeches from New York City Mayor Fiorello LaGuardia, Yankees manager Joe McCarthy and Gehrig's old pal, Babe Ruth, it was time for The Iron Horse to address the crowd of 61,000.

"Fans, for the past two weeks you have been reading about a bad break I got," Gehrig said into the microphones at home plate. "Yet today, I consider myself the luckiest man on the face of the earth."