#1 Leicester City
Leicester City won the 2015-16 league title, out of nowhere, surprising the entire world of football in the process. During a scintillating streak of matches, they overpowered every team they came up against in the league, including the 'Big Six'. The Foxes won 23, drew 12, and lost 3 in 38 matches, eventually winning the league with 81 points in the bag.
Their historic achievement that season was widely praised all over the world and key players like Vardy, Mahrez, and Kante came from the shadows to be regarded as top-notch talent.
However, the Leicester squad couldn't keep up their great run the next season. Their horrible title defense, in 2016-17, was conducive to the sacking of Manager Claudio Ranieri, who had led them to the league title only about a year ago.
Eventually, the Foxes lost more matches (18) than they had won (12) in that season. Under new manager Craig Shakespeare, they finished at 12th on the league table with only 44 points, a serious downgrade from their title-winning season.