Chelsea won the English Premier League title last season by eight points and with three games to spare. It was hard to find a weakness in the team, and there was talk of Jose Mourinho building a dynasty at Stamford Bridge.
Seven months later, Mourinho is gone and Chelsea is back in a state of flux after possibly the most stunning decline ever seen in English top-flight football.
Mourinho was fired Thursday with Chelsea just one point above the relegation zone after losing nine of its 16 league games this season.
How did it fall apart so quickly?
Here are some of the reasons:
This time, Mourinho said, it would be different.
After 2 ½ years at Porto, three years and three months in his first spell at Chelsea, two years at Inter Milan and three years at Real Madrid, Mourinho came back to Stamford Bridge in June 2013 declaring himself "The Happy One" and saying he was ready to start a long reign in his second spell at Chelsea.
But his latest managerial stint has once again been relatively brief, lasting 2 ½ years. Mourinho simply can't find a way to stay at a club for the long term.
Maybe the intensity in his coaching methods fizzles out. Maybe his abrasive, provocative style that can initially get the best out of players gets tiresome in the end. Players may simply get wary of Mourinho and his ways after two or three seasons.
Mourinho acknowledged in a tirade against players after the loss to Leicester on Monday that his team played at a level "more than they really are" in cruising to the league title last season.
Chelsea had taken advantage of a Manchester United in transition, a Manchester City on its usual comedown the season after winning the league, a Liverpool minus Luis Suarez, and a typically inconsistent and injury-hit Arsenal.
It was unrealistic to expect Chelsea to enjoy a similar ride this season. Still, the regression has been more shocking than anyone could have predicted.
Mourinho signed a new four-year deal in August but was no longer "The Happy One" at the start of this season, following a summer in which he failed to sign his preferred transfer targets.
There's a saying in football that you should build from a position of strength. Chelsea didn't.
The club was rebuffed three times by Everton in its pursuit of center back John Stones, despite the player handing in a transfer request. Chelsea was also interested in France midfielder Paul Pogba, but he stayed at Juventus. Then goalkeeper Petr Cech, a leader and key squad member in Mourinho's eyes, was sold against the manager's will to Arsenal.
In the end, Mourinho brought in injury-plagued striker Radamel Falcao, backup defenders Papy Djilobodji and Baba Rahman, backup goalkeeper Asmir Begovic and winger Pedro Rodriguez from Barcelona.
Only Begovic can be said to have been a success.
Mourinho caused a stir by criticizing the actions of two members of his medical staff, Eva Carneiro and Jon Fearn, when they treated an apparently injured Eden Hazard late in Chelsea's opening game of the season — a 2-2 draw against Swansea.
Mourinho called the pair "impulsive and naive" and downgraded their duties, which included their removal from the bench on match days. Carneiro is currently taking legal action against Mourinho.
Mourinho's reaction was denounced by many throughout the game. He is known for finding a distraction or a scapegoat to deflect attention from his team's shortcomings, but this was seen as a step too far and an indication that things weren't quite right.
He may have lost respect in the dressing room, too.
To a man, apart from right winger Willian, every one of Mourinho's regular starters have underperformed this season.
Captain and defender John Terry was substituted at halftime against Man City in September and then early in the second half against Leicester on Monday. Fullbacks Branislav Ivanovic and Cesar Azpilicueta — two more key players in the title-winning campaign — have been exposed time and again.
Cesc Fabregas has looked off the pace and been dropped, while fellow central midfielder Nemanja Matic has lost his edge and drive.
Oscar has been anonymous, Hazard — English football's player of the year last season — still hasn't scored this season, and Diego Costa has been more interested in picking a fight than scoring goals. Costa and Hazard were the team's main source of goals last season. This season, they have just three goals between them.
Clubs often experience a dip in form and motivation the season after winning the league, but the slide has been extraordinary at Chelsea.
Mourinho has paid the price.