The Atlanta Braves were +1000 to win the World Series before the season started. By the time the regular season was done, their odds had gotten worse.
At the beginning of the playoffs, the Braves were +1100 to win it all. They'd lost Ronald Acuna Jr., one of baseball's best players, to a torn ACL back in July. They were 88-73 and held on to win a bad NL East. There was no real reason to think they were heading to the World Series.
The Braves upset the Los Angeles Dodgers in the NLCS to advance to the World Series.