We looked at Southampton’s defensive form last week and were mightily impressed by their numbers. After an 8-0 thrashing of Sunderland we’re going to have a quick look at some advanced football stats and see if the Saints are genuine challenges for a top 4 place in the Premier League this season.
The chart below shows an advanced stat called ‘Expected Goals Difference’ or xGD. It’s like regular goal difference, but instead based on ‘Expected Goals’ and the quality and quantity of chances a team creates compared to it’s opposition. We’ve adjusted for opposition strength so far too.
xGD is represented by the length of the bars. Over on the top right are teams that create more quality chances than their opponents and thus should win more games. Teams to the left are in negative xGD and are teams that will probably lose more games than they win. The colour of each bar is important too. If you are familiar with a stat called PDO then it’s the equivalent but using xG. We call it GDO; Goal Difference Offset. It’s the difference between actual goal difference for each team and their ‘expected goals difference’. Teams in blue have a high GDO - they've scored more goals and conceded less then the number/qualityof chances alone would suggest, and can be considered to hve played brilliantly or got lucky at times. Teams in orange have scored less and/or conceded more and have been rubish/unlucky.
As you can see Southampton are in the top 4 for xGD and have had a very healthy GDO and scoring rate from those chances. This is why they are sitting pretty in 3rd place in the Premier League table and boast a goal difference of +14, second only to a rampant Chelsea. It’s also why they are doing much better than other teams near them in this table and in particular Arsenal. The Gunners are up to their old tricks, and failing to finish the numerous decent chances they create whilst at the same time conceding from the few they do give up.
PDO has been proven to regress to the mean over the course of the season. So will GDO. Team’s can’t maintain crazy scoring rates or pull off super saves game after game. Eventually life evens itself out. Southampton have enjoyed a real purple patch so far this season, a combination of playing at the top of their game and facing the right opposition at the right time. They won’t be able to maintain this. At some point Pelle will miss a few decent chances and Forster will fluff an easy save.
However, that being said, xG and xGD have been proven to be repeatable and an able predictor of what happens next. More repeatable than actual goals scored or conceded, and certainly a lot better predictor than points scored. This is why we base a lot of what we do at insideFPL and stats like these. What Alan Shearer says on MOTD is true; if you keep getting chances, you’ll score. And this applies for both teams and players. On any given day a team can miss open goals or score a 40 yard screamer, and all teams will go through good and bad spells. Over time the teams who can create the best opportunities will prevail, which brings us back to the Southampton. Despite possibly 'over-performing' their raw chance creation numbers, they are still right up there for ‘Expected Goal Difference’ and mixing it with the regular top 4 contenders, and this bodes very well for the rest of the season.
What, then, are the implications for fantasy football managers? This means we should forecast Southampton to be challenging for Europe at the end of the season, and possibly pushing the likes of Arsenal and Liverpool for 4th place for long period of the season. For fantasy managers, this means Southampton are looking likley to replicate Eveton's form last season. They are going to continue scoring goals and winning games. When they come up against the very top teams we should expect them come out with some credit and score a few goals. Against their direct rivals for Europe like Everton and Spurs, they should be consdiered the favouraites to win the game..
You can’t help but notice Newcastle just below Southampton in the above chart. They’ve created a lot of chances and conceded relatively few but have just not been able to score, whilst at the same time leaking goals. They are the opposite of Southampton, and indeed got turned over 0-4 by Koeman’s team. We don’t know exactly what to make of Newcastle at this point. Their biggest downfall has been hitting the target. Their shot accuracy of 24% is only better than Aston Villa’s and way behind Southampton’s league leading 47%. Both these vlaues will even out towards the typical league average of around 33% but by then Pardew’s team could be in big trouble. A bad run of games can really sap the confidence of a team, affecting the approach in games from the coach as well as that of the opposing manager and players, From a fantasy perspective we’d say there is potential at St James’ Park, and to keep an eye on the Magpies finding their scoring boots. Until they do though, they are definitely one to wait and see on before making any move.