In recent weeks and months I’ve read a couple of snippets posted on Twitter about Sunderland and their expected goals (xG) performance, namely from Mark O’Haire, George Elek and Ted Knuston, which has caused quite a reaction from parts of the Black Cats fanbase.
For what it’s worth here’s my take on how I rate Sunderland, why they are overperforming xG and whether it is sustainable.
NOTE: For those not familiar with xG this is a metric to monitor the quality of goalscoring chances. A value between 0 and 1 is assigned based on the probability the chance will result in a goal. A 1 in 20 long range shot with have a probability of 5% (an xG of 0.05) whereas a penalty has a 3 in 4 expectancy and therefore an xG of 0.75.
Sunderland 2018/19 xG Performance
| GF | GA | GD | Points | Rank | |
| Actual Performance | 42 | 20 | 22 | 44 | 2nd |
| Expected Performance | 24 | 25 | -1 | 28 | 16th |
My xG model, like others, ranks Sunderland considerably lower than the 2nd place they currently find themselves in. The area in particular which sticks out is the goals scored. In simple terms they were expected to score 24 goals from the chances created so far this season but have scored a whopping 42.
On a match by match basis, Sunderland have only outcreated opponents based on xG in 9 of the 21 games with a clear split between performances at home and away.
At the Stadium of Light performances have been strong, winning xG on 7 of the 10 matches, and reflecting the high points haul collected. Away from the North East they have only won xG on 2 of the 11 occasions and it is here when Sunderland appear to be vulnerable. The Black Cats have consistently conceded chances on the road which the opponents have failed to capitalise on.
Looking purely at shot conversion rate, Sunderland’s opponent have the second lowest rate. At the other end of the pitch they are converting their chances into goals at the highest rate in the whole league. These numbers are why the Black Cats find themselves in the automatic spots heading into the festive period.
Those numbers look very good but as xG shows they are experiencing an overperformance particularly on the attacking side.
An xG overperformance in the short term is entirely feasible and actually quite common. Over the longer term one of two things tends to happen (i) the number of goals scored reverts back in line with expected goals or (ii) an increase in performance maintains the inflated level of goalscoring. Sunderland are an anomaly as we are now 22 games into the season (21 in Sunderland’s case) and so far, neither has happened.
So what’s driving this? Is Sunderland’s attack so superior to the remainder of the league that an xG model is not sufficiently capturing the quality of the squad?
Sunderland 2018/19 Shots
The first thing to point out is that Sunderland have been very accurate with the chances they have created.
| Shots on Target % | Rank | |
| Sunderland | 42.2% | 3rd |
| League Average | 37.2% |
They rank third for shots on target behind only high performing Luton and fellow xG overperforming Peterborough. This may be due to a superior quality of player but has been aided by the high proportion of shots taken from around the penalty spot area (25%) compared to the remainder of the league (20%).
The problem why their expected goals scored is low is the number of attempts Sunderland have taken.
| Number of Attempts | Rank | |
| Sunderland | 223 | 21st |
| League Average | 256 |
Only three teams have had fewer attempts. On the other hand, fellow promotion rivals Barnsley (321), Portsmouth (287) and Luton (281) all have a significantly higher number of attempts and hence are all rated superior by xG numbers. It may be that the attackers have been more selectively with chances, waiting for a better shooting position before pulling the trigger, something which won’t be captured in my xG model.
The resultant of so few shot attempts means Sunderland need to be clinical – and they have. As shown in the chart earlier no one is taking chances at the rate of the Black Cats.
Sunderland 2018/19 Attacking Performance
Josh Maja has been the standout performer in terms of goals with 12 in the league to date. Though a word of caution is that he has scored 8 goals more than expected using xG and is therefore experiencing a hot streak which is unlikely to continue. In addition, Maguire, Gooch, McGeady and Cattermole have added another 19 goals, a further 8 goals than expected using xG.
Looking at the players to score 10+ league goals this season Maja has the standout shot conversion.
| Team | Player | Minutes | Shots | Goals | Shot Conversion |
| Gillingham | Thomas Eaves | 1759 | 57 | 14 | 25% |
| Doncaster Rovers | John Marquis | 1980 | 59 | 12 | 20% |
| Rochdale | Ian Henderson | 1979 | 49 | 12 | 24% |
| Sunderland | Josh Maja | 1347 | 29 | 12 | 41% |
| Plymouth Argyle | Freddie Ladapo | 1770 | 53 | 11 | 21% |
| Charlton Athletic | Karlan Ahearne-Grant | 1711 | 38 | 11 | 29% |
| Barnsley | Kieffer Moore | 1656 | 66 | 11 | 17% |
| Charlton Athletic | Lyle Taylor | 1862 | 51 | 10 | 20% |
| Luton Town | Elliot Lee | 1593 | 61 | 10 | 16% |
| Peterborough United | Matthew Godden | 1556 | 36 | 10 | 28% |
12 goals from 29 attempts (41%) is remarkable as the other top goalscorers range between 16% and 29%. To maintain this goalscoring performance Josh Maja will have to be one the best finisher the league has ever seen. Very unlikely.
He’s also be aided by team mates scoring low probability chances at a higher rate than expected as shown by a selection of videos below.
Gillingham Away
George Honeyman and Max Power score in quick successions to put Sunderland 3-1 up.
Peterborough Home
Josh Maja scoring through multiple bodies to put Sunderland 1-0 up.
Southend Home
Chris Maguire scoring a long range screamer to put Sunderland 2-0 up.
Plymouth Away
Aiden McGeady this time scoring from outside the box to put Sunderland 1-0 up.
The numbers say to me that Sunderland will experience a dip in results, most likely away from home, starting this weekend in the big game away at table toppers Portsmouth.
EFL Numbers 