Don't know why you say goodbye

On this day 44 years ago, Paul McCartney walked away from the Beatles. C Flanigan/Getty Images

On this day in 1970, Paul McCartney stunned the world when he announced he would be leaving the Beatles. In honor of his monumental announcement, we look back at five shocking departures in the sports world.

1. Michael Jordan: The three-time reigning NBA champ and Finals MVP shocked fans everywhere when he announced his retirement from basketball on Oct. 6, 1993. He further surprised everyone when he signed a a minor-league baseball contract with the Chicago White Sox just a few months later. In March of 1995, Jordan announced his return to basketball and helped lead the Chicago Bulls to three additional NBA titles.

2. Lorena Ochoa: The No. 1 golfer in the world announced her retirement in April of 2010 at just 28 years old. Ochoa had held the No. 1 ranking on the LPGA Tour for 157 consecutive weeks, so fans and her peers were shocked by the news. She cited her desire to start a family as the reason for her departure, and she and her husband have since had two children.

3. Wayne Gretzky: On Aug. 9, 1988, the hockey world was turned upside down when the Edmonton Oilers announced they had traded their superstar and beloved native son to the Los Angeles Kings. Known today simply as "The Trade," even the Canadian government tried to get involved to block the deal from being finalized. Much to the dismay of Oilers fans and Canadians, Gretzky moved to Los Angeles and helped lead the Kings to their first Stanley Cup finals appearance in franchise history in 1993.

4. Marion Bartoli: After more than a decade on the WTA Tour, the 28-year old finally won her first Grand Slam at Wimbledon in 2013. The next month, she shocked the tennis world by announcing her immediate retirement after a loss at the Western & Southern Open. Citing chronic injuries and a lack of energy, Bartoli walked away from competitive tennis ranked No. 7 in the world.

5. LeBron James: After seven seasons with the Cleveland Cavaliers, the reigning MVP became an unrestricted free agent after the 2009-10 season. In a national TV special called "The Decision" on July 8, 2010, James announced he would be joining the Miami Heat. Cleveland fans were furious over the move and team owner Daniel Gilbert posted an open letter to the superstar on the team website in which he called James "heartless" and "callous" and the decision a "cowardly betrayal." James has since won two NBA titles with his new team.