We looked at the term ” Expected goals” in our last article and what it entails. We would now look at its usefulness as it is affecting the footballing sphere. Let us still emphasize that its potential uses goes far beyond the critiques of a player’s finishing.
Why is Expected goals Useful?
There are basically two ways that clubs and analysts are addressing its usefulness: one concerning teams and the other concerning individual players.
Measuring team Performances
Expected goals rates the quality of a chance,rather than its actual outcome. It can be used to rate process over results.
Though results in football can be influenced by luck and randomness, we feel agitated as fans seeing our team dominate the game only to see them other team score at the first chance at goal. These are not sustainable ways to win a game and expected goals gives us clues about teams that would be able to change their fate once their bad luck of losing games comes to an end. Its stats will convince us that these teams will go on a good run once their bad luck comes to an end.
One important example is Juventus in 2015-16 season. They started d the season poorly, just winning three of their first ten games but their expected goals numbers were excellent. They were dominating most of their games though not converting their chances.
The Bianconeri persisted and their luck ran in, winning 15 matches in a row. They became Champions at the end of the season with 9 points. In those situations many clubs would have panicked either sacking their manager or changing their strategy but they sticker to what they know how to do best. Expected goals helped in that circumstances.
With Expected goals, one can predict who wins the league. For example, Manchester City has led the rest in terms of xG by a comfortable margin this season.This suggests that they would rightly earn their place as champions, come end of the season.
Interestingly, Chelsea are way down 10th position while Crystal Palace, 8th despite their struggles. This suggests that Antonie Contested has work to do within the Chelsea dressing room in order to put them back as title contenders while Roy Hodgson would be glad to find team in such position and find joy to improve in Selhurst Park.
Huddersfield Town are bottom in the league in expected goals and not surprising they suffered heavy defeats lately
Measuring individual performances
As well as comparing a team’s expected goals to their actual goals scored, players are also hitting more or less than their expected goals numbers. When a player is over performing more than his xG, we can suggest he is either lucky or an above average finisher. If he surpasses his expected goals over a few match and does not have a prolific goal scoring record, we can also say he is on a hit streak that would not last forever.
But someone like Harry Kane, who expressions more goals than the chances he amasses year after year is clearly better in front of goal than the former.
This can assist clubs in decision making process. This can help in identifying a player that is good in positioning himself before they started scoring handful of goals that teams could notice.
Two potential examples are Swansea’s Tammy Abraham and Watford’s Richarlison who rank among the players with highest expected goal ratio despite playing for clubs below the mid table that don’t create as half chances as the top teams.
These two players are under the watchful eyes of the top teams, or though Chelsea would be giving an opportunity when he comes back from loan, in Abraham’s case.
Expected goals can also be helpful in determining whether a player’s form will be sustainable across the season.
Mohammed Salah, for example will probably slow down slightly eventually, though his individual expected goals as of December 1 was an impressive 8.53, it was short of the 12 goals he had actually netted
Why does expected goals get criticism?
As with many statistics, the criticism of expected goals is often borne out the poor use of it. Expected goals for many individuals, for example, are useless without context. If a team scores some goals at the most difficult chances, they may fall back to protect the lead. If their opponent then ends up with a higher expected goals number by taking low quality shots, we may not conclude that they deserve to win the game.
This is the challenge statistics analysis always have: if the raw numbers are not perfect, it gives critics the ammunition with which to take aim at.