Overperformers and underperformers in the Premier League top six
This article takes a statistical look at the top six sides to find out which sides are overperforming and underperforming. It also takes a look at the issues plaguing each side and what they need to correct to improve in the near future. This Premier League season has been full of ups and downs, largely the latter for most sides but mainly positives for current leaders Liverpool.
The top four race is far from decided as there are at least six to seven teams who can qualify for the Champions League. However, by looking at the Expected Goals (xG) for each side, it is possible to determine which sides are clinical and lucky and which ones are not.
What is Expected Goals(xG) and Expected Goals Against (xGA)?
Expected Goals is a statistical metric used by analysts and data scientists to look at the underlying statistics to see how a team is actually performing without looking at the results in isolation. For example, if a forward is faced with a one-on-one situation against the goalkeeper or is lining up for a penalty, more often than not the forward will be expected to score. This means that there is a high probability of a goal and therefore the Expected Goal(xG) would represent a high probability like 0.75, 0.7 etc.
The probability of any event happening is always between 0 to 1 where 0 is that the event cannot happen and 1 being the event sure to happen. Therefore if we look at the xG, we can find out if a team is overperforming or underperforming by analyzing whether their actual stats reflect their performances on the pitch.
Similarly, Expected Goals Against acts as the indicator for the defensive performances by analyzing the types of shots that a team concedes and therefore how likely they are to concede in every match.
Expected Points is a large scale metric which combines all the smaller metrics like xG, xGA etc. It looks at the larger picture and calculates the number of goals each team should have scored and conceded based on their xG and xGA. After calculating this, such individual values from each match are considered to see how it would have affected the result of that match. For example, if a team A has an xG of 1 and the opposite team also has an xG of 1 but team A wins 2-1, the expected result would have been a draw. Therefore, the Expected Points for team A would have been just one point.
Liverpool are yet to lose in the Premier League.19 wins, one draw and zero losses mean that the Reds are miles ahead of second-placed Leicester. The gap is currently at 13 points and barring a massive collapse, Liverpool look set to win the league with ease.
Liverpool have scored 49 goals so far with an xG of 43, which means they have overperformed their expected number by six goals. Jurgen Klopp's side have been quite lucky with the VAR calls and refereeing decisions this season but this takes nothing away from their imperious form. Although they may be overperforming offensively, they have very few inherent problems in their side barring maybe squad depth to a certain extent.
The reigning European champions' expected points at this stage is just 42, a massive difference of 16 points. However, it has to be said that the side winning the league always involves a fair share of luck and Liverpool can claim the same. This does not reflect much on the fact that they are a cohesive, consistent and ruthless machine.
2. Leicester City
Can Leicester City live out another fairytale? Few can forget their memorable title win a few years ago but some intelligent recruitment, strong team spirit and a meticulous coach mean that Leicester are back at the top end of the table as the Foxes sit second with 45 points.
They have scored 46 goals and conceded 19 while the xG and xGA metric has them with just 36 goals scored and a significantly more 26 goals conceded. This reflects that Leicester, like Liverpool, are overperforming and have an element of luck. Leicester's starting eleven has the pace, technique and power to beat any team in England but if injuries strike, the same cannot be said about their deputies.
As the season goes on, injuries to the likes of Jamie Vardy, James Maddison and Caglar Soyuncu could easily bring Leicester down to earth. Nevertheless, they should finish in the top four quite easily even if the xG reverts to the mean.
3. Manchester City
Pep Guardiola's City have had a rough campaign so far ravaged by injuries. They have already lost five games and sit in third with 44 points. The significant issues for City have come from injuries and a lack of depth in key areas. Aymeric Laporte's injury has been the biggest factor in City not having good defenders which has resulted in Fernandinho playing in defence and John Stones and Nicolas Otamendi being unreliable.
City's xG is 55 and they have scored 56 goals indicating that they are scoring the number of chances the are expected to convert. However, defensively, City are extremely susceptible to counter-attacks and being hit on transitions. They have conceded 24 goals, just one less than Manchester United, with an xGA of 22.