The 2007 New England Patriots are proof that the Golden State Warriors aren't guaranteed to repeat as NBA champs despite their incredible 50-5 start to the 2015-16 season.
Remember those Pats? They were 16-0 in the regular season, won two playoff games and then blew an opportunity to complete the NFL's second perfect season by losing Super Bowl XLII to the Giants in February 2008.
The 1990 Oakland Athletics were another so-called sure bet to not win a championship, as they were swept by the Cincinnati Reds in the World Series after winning a MLB-high 103 games in the regular season and sweeping the Boston Red Sox in the ALCS.