(CNN) Oh Jose, how did it come to this?

From celebrating a championship in May to looking for a new job by Christmas. Jose Mourinho has been sacked by Chelsea after a disastrous run of form which has left the English Premier League titleholder languishing near the foot of the table.

The ax finally fell on one of the most successful coaches in world football following Monday's 2-1 defeat to Leicester -- the team's ninth loss in 16 league games.

So what went wrong for the "Special One?"

How bad is it?

It's less than six months since Chelsea was celebrating winning the Premier League title after finishing eight points clear of its nearest rival.

Diego Costa scored 20 league goals in his debut season and Eden Hazard was named Player of the Year by his fellow professionals and the English sports media.

Mourinho, who rejoined the club in 2013, six years after leaving Stamford Bridge, appeared set to lead the club into a new era of dominance.

How times have changed.

Chelsea sits 16th in the Premier League -- 20 points adrift of surprise leader Leicester.

Mourinho's side has also suffered shock losses to Crystal Palace, Southampton and West Ham, as well as a painful 3-1 defeat to Liverpool in October.

Lost the dressing room?

One of the most common phrases chucked at under-fire managers is that they have "lost the dressing room."

And one way to royally annoy your players is to accuse them of betrayal.

After Monday's defeat at Leicester, Mourinho was frank in his criticism of his charges.

"One of my best qualities is to read the game for my players, and I feel like my work was betrayed," he said.

Never lacking in self-belief, he did offer an alternative view on his team's struggles.

"One possibility is that I did an amazing job last season and brought the players to a level that is not their level and now they can't maintain it," he speculated.

The Eva Carneiro saga

Since the opening day of the season, Mourinho's decision to criticize club doctor Eva Carneiro has led to questions about his judgment.

Carneiro was dropped from first-team duties and labeled "naive" by Mourinho for treating Hazard during August's draw with Swansea at Stamford Bridge, and she has subsequently left the club.

While Mourinho was cleared by the English Football Association of making discriminatory comments towards Carneiro, the saga has arguably left a stain on his reputation.

The Women in Football group said it was "appalled by the conclusion of the FA investigation" and there have been widespread reports in the UK media that Carneiro has served notice of a claim of constructive dismissal against Chelsea.

"I'm not aware we have received any paperwork so we will keep to our stance that it is an internal staffing matter," a Chelsea spokesman said at the time.

John Terry finished?

He has been the rock on which Chelsea's success has been built, but is captain Terry's time at the top finished?

There is little debate that he has been one of the outstanding defenders in European football over the past decade, but at 34 he is entering the twilight stage of his career.

During Mourinho's first spell in charge at Chelsea, Terry was the man entrusted with enforcing his instructions on the field -- which he did to great effect.

That Chelsea team won the Premier League title in 2005 and 2006, dominating English football and leaving rivals in its wake.

JUST WATCHED Looking back on Mourinho's Chelsea reign Replay More Videos ... MUST WATCH Looking back on Mourinho's Chelsea reign 02:36

Terry played every minute of last season's league campaign and was rewarded with a new one-year contract, but has since become a bit-part player and was controversially hauled off at halftime in the 3-0 defeat at Manchester City.

He's even been linked with a move away from the club, though Mourinho has said the bond between the two men remains as strong as ever.

"He's a player of my total confidence," Mourinho told reporters in October. "I trust him as always and he's one of my men. Because he's on the bench one game or because I take him off at halftime, nothing changes."

Hazard warning

Last season, the diminutive Belgian could do no wrong. Hazard glided through the campaign and picked up the Player of the Year award following a series of outstanding performances.

His ability to conjure something out of nothing gave Chelsea an extra edge to their play and left opponents bamboozled -- but that has all changed this season.

The 24-year-old has seemingly lost his mojo.

He scored 19 goals for Chelsea in all competitions last season, but is yet to find the net for the Blues this campaign.

Indeed, the relationship between Hazard and Mourinho has deteriorated to such an extent that reports suggested the player had exaggerated a hip injury which forced him off during the Leicester match.

Hazard's father denied the reports and insisted the pair still enjoyed a good working relationship.

Not anymore...

Men in black

Mourinho has never been one to shy away from controversy -- or voicing his dissatisfaction with referees.

And this season has proved that old habits die hard, a fact supported when Mourinho was sent to the stands during Chelsea's 2-1 defeat at West Ham.

He was charged with misconduct by the FA after going to speak to the referee during the interval at Upton Park, which is strictly prohibited, and fined £40,000 ($60,000).

Mourinho was also in hot water with the FA earlier in October after his side lost 3-1 to Southampton at Stamford Bridge.

He went on the offensive after the game, claiming officials are scared to give his team penalties when referee Robert Madley decided not to award Chelsea a spot-kick -- a rant which led to the Portuguese manager being fined £50,000 ($75,000) and given a suspended one-match stadium ban.

"He was afraid to give it like everyone else is afraid to give it," Mourinho said.

"If the Football Association wants to punish me, they can. They don't punish other managers."

Three-year itch?

The great Hungarian coach Bela Guttmann once proclaimed that the third year of a manager's reign could prove "fatal."

Guttmann, who led Benfica to the European Cup in 1961 and 1962, never stayed at a club for more than three years -- and neither has Mourinho.

Guttmann led Benfica to European glory in the 1960s

Mourinho, who has won the Champions League with Porto and Inter Milan, is without doubt one of the best in the business.

But he was unable to arrest Chelsea's slide.

While Chelsea could quite conceivably still finish in the top four and qualify for next season's elite European competition, the Premier League title already looks to be gone.

What do you think?

Who should replace Jose Mourinho at Chelsea?