Posted on 3rd November 2015

The reigning champions of England currently* lie 15th in this season’s league table, having lost 6 of their first 11 league games.

Chelsea only lost three league games in the whole of last season.

What is going on?

How can a team who won the league so comfortably just 5 months ago now find itself near the relegation zone? Have Chelsea just been unlucky so far this season? Are their results due for an almighty reversion to the mean? Is it possible that the bad results are all down to some anti-Jose conspiracy between the media and the referees?

I work for an analytics and software company called OddsModel. I help them to look at underlying statistics to get a better understanding of a team’s performance than it’s possible to get with raw results alone.

A useful underlying number to look at is Shots On Target Ratio (SotR). Over time a football team will generally get the results it deserves based on how many shots it manages to get on target relative to its opposition. We can express this ratio as a simple percentage – so an average team in a league will have a SotR of 50%.

It is possible for really good football teams to have prolonged spells of bad luck, where their results are much worse than their actual ability, and a stat like SotR can identify such cases. Borussia Dortmund last season are a good example. They found themselves in the relegation places at Christmas. But their underlying numbers were still good – they were just on the wrong end of a bad bit of randomness, which in a low scoring sport like football can translate into an horrific looking set of short term results.

But such an aberration will ALWAYS revert to the mean eventually, so long as the club holds its nerve. They did, and it did. Dortmund finished the season strongly and ended up in 7th.

Bund 14_15

Not everyone likes looking at football through ‘stats’, but Dortmund last season is a good example of an occasion where gamblers, analysts and decision makers at the club itself needed to hold their nerve – even when they were languishing at the bottom of the table.

*(as at 2nd Nov ’15)

But Chelsea are NOT like Dortmund last season.

Chelsea are a team who have genuinely and inexplicably declined. Massively. Their underlying numbers are, if anything, worse than their bare results this season.

Their decline is not something that started at the beginning of this season. The seeds were sown half way through last season, when their underlying numbers sarted to decline, even though this drop off was largely obscured by their (apparent) stroll to the title.

Che 14_15

It is a myth though that Chelsea won the league comfortably last season – despite their final supremacy in points (8 points clear of Man City). They were undeniably terrific in the first half of the season. A SotR of 67.3% is outstanding. By way of comparison, European champions Barcelona have managed 72.3% since the start of last season, and Bayern have managed around 70% in recent Bundesliga seasons. 67% is a really impressive number in the Premier League. But we can see their SotR numbers fell off pretty dramatically in the second half of the season, by more than 10%.

They still won the league by 8 points though – how? Well, their run-in was littered with one-nil wins, where Courtois, Terry and Matic helped them keep a clean sheet, leaving Hazard and Costa to nick a winner at the other end. It was impressive in its own way. But pulling off those sorts of results, while your underlying numbers are bad, is not sustainable long-term. That’s a high-wire trick that just needs one things to go wrong for all it all to come crashing down.

And Chelsea have well and truly fallen to earth this season.

SotR 14_15

They have NOT been unlucky. If anything, they have more points than they deserve.

We can safely dismiss the ridiculous idea that it is biased referees who have been costing Chelsea. Referees have (virtually) no influence on the number of shots a team takes. Chelsea have just been awful. The idea that officials or the media are to blame is simply nonsense.

We doubt anyone actually foresaw just how far Chelsea would regress, but you could say their declining SotR % is simply folowing a consistent pattern over the last year.

Chelsea SotR

It is always tempting to reach for a single definitive reason to explain something like Chelsea’s fall off the cliff. But usually these things occur as a result of a combination of factors. Such as….

1. “Complacency is a disease”. So said Sir Alex Ferguson recently. He was a master at maintaining a hunger for more success, never dwelling too long on past glories. But neither Man City nor Chelsea have come close to retaining their titles after winning the English league in recent years. In the summer the Chelsea players had the glory of a Premier League title to bask in. Their manager got a four year contract.

2. Inadequate pre-season. Chelsea players came in later than all the other clubs ahead of this season. Jose gave his players a full month off in the summer. Diego Costa admitted he came back in overweight, and the whole squad looked way off the match fitness levels of the start of last season. It is incredibly unlikely for a number of proven world class players all to lose form simultaneously – as has happened with Terry, Ivanovic, Fabregas, Hazard and Costa – without there being a common physical contributing factor.


3. Eva Carneiro-gate. Jose’s bizarre reaction and tirade against his physio and doctor can’t have been popular in the dressing room.

4. Transfers. While the popular narrative about Mourinho’s trophy-laden career is that his success is down to his brilliance as a coach, the truth is that his clubs have only done just about as well as you would expect given the amount that they have spent on transfers and wages, relative to their competition. In the last couple of seasons Chelsea have signed lots of mid-range players who haven’t got anywhere near establishing themselves as first team regulars, but haven’t spent lavishly as they have in the past under Mourinho. Kevin De Bruyne and Romelu Lukaku were allowed to leave for way under their current market value. It is hard to imagine that this current Chelsea side wouldn’t be a lot stronger with those two in it, and with Cech, Salah, Schurrle, Cuadrado etc in the squad. This summer the club failed to get Jose the one player he seemed to really want; John Stones.

falcao5. Falcao. The Falcao to Chelsea deal this summer stinks. For any striker who relies on explosiveness of movement for his edge, when that explosiveness is lost through age or injury then he is finished as a top level player. It doesn’t matter how good he was. Falcao was an awesome centre-forward a few years back at Atletico, but when he did his ACL in 2014 he was (sadly) done as a top striker. His decline matches similar types Fernando Torres and Michael Owen; dynamic world class goal-scorers in their early twenties, robbed of their edge by injury in their mid-twenties, leaving them as free-transfer fodder by their late twenties. Falcao is done. He’s gone, and he isn’t coming back. That has been apparent for a while. The other players in the Chelsea squad will have known this full well when he was signed. There is no way Jose didn’t know this. And there is no way he would have signed Falcao if his agent wasn’t Jose’s friend and business partner Jorge Mendes. That deal stinks.


6. The brightest stars fade the fastest. Mourinho brings a huge ego and personal charisma with him to his place of work. It’s all about him. But his paranoia about officials, the media, UEFA etc. (recurring themes at every club, and in every country he manages) is tiresome after a while. The galvanising effect of his presence in a dressing room probably has a limited shelf-life, before his players come round to the same way of thinking as most of the media and football fans – this guy is a narcissistic sociopath, and really just a bit of a prat. His petulant recent post-match interviews can’t inspire any respect from his players. He has never enjoyed prolonged success at any club. You could say he is a specialist in long-term failure.

Screen Shot 2015-11-03 at 14.01.147. Burn-out. Mourinho doesn’t rotate his squad. He puts an enormous toll on his top players. Why does he play the likes of Eden Hazard, Willian, Cahill and Terry for 120 minutes in a league cup tie on the Tuesday in between two Saturday Premier League games, and a week before a Champions League tie, as he did last week at Stoke? Is it because he thinks it’s the best thing for the players? For the team? In the best long-term interests of the club? Or because he wants to win every trophy he can in the short-term in order to bolster his own managerial record, at the expense of the long-term interests of players and club?

8. Lost the dressing room. Nine times out of ten, when the question is ‘should a club sack their manager?’ the smart answer is ‘probably not’. Many clubs panic by over-reacting to a short-term blip in results, when those results will revert to the mean regardless of who is in charge. The club can save themselves the hassle and expense of changing their manager by sticking with the one they have.

But one time out of ten it is definitely not only right to remove the manager, but also vital to do it as soon as possible. This is when the manager ‘loses the dressing room’.

The two biggest factors in the performance of any football team are a) the raw talent of the players, and b) the intensity with which they play. Tactics are relatively unimportant. If Chelsea’s players are playing without intensity because they would like to see Jose get sacked then their results will NOT revert to the mean that their talent deserves. They will keep getting worse until he gets sacked, or the players are replaced.

At OddsModel, because we look at underlying statistics to get a better understanding of a team’s performance, Chelsea’s decline is not a huge surprise to us (though we can’t claim to have known they would be THIS bad!).

We maintain ratings for football teams in all the major European domestic leagues. Our ratings help our professional gambler clients get an edge, and make a profit trading in online football betting markets.

We take into account underlying statistical performance and also adjust for changes in playing personnel and management. Below is the graph of Chelsea under Jose Mourinho’s since he returned in the summer of 2013. It tracks our rating for Chelsea’s ‘Supremacy’ (expected average goal difference) – a measure of their ability to score more goals than their opposition.

Chelsea OM Rating

Mourinho inherited a good team. They got steadily better until around Christmas 2014. But since then they have been in decline. This huge drop off this season is a rare shape for any football team. It only normally comes after a club gets into financial difficulty and has to have a fire-sale of players, or where a manager loses the dressing room and the players want to get him the sack.

So should Chelsea sack Mourinho?

Ask yourself a question. Would you increase Chelsea’s Supremacy rating if you heard that Chelsea had sacked Jose? We would.

It seems likely that Jose has to a lesser or greater extent ‘lost’ the dressing room. If this is the case then things will only keep on getting worse.

It is easy to imagine that the leaders in the Chelsea dressing room are Terry, Fabregas and Hazard. If it’s true that Jose has these three against him now (he has dropped and subbed off all three this season) then there is no way back for him. If the loyalty of the players is broken, and Chelsea keep him as manager for the rest of the season they could feasibly even be relegated.

Seriously, they could.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s