I posted something like this on twitter after the last round of games:
Which led to a good (not noob) question:
@footballfactman Some noob Qs: Big diff in Allis xG v Actual. Can we infer anything from this disparity? Predict anything? A cooling maybe?
— Tony (@Tony_The_Red) January 4, 2017
I reckon the best way to answer such a question is by using probability distributions (I promise it won’t twist your melon, man). You’re basically lumping together all the player’s shots over time and seeing how many goals they’d likely score from them.
Let’s take a look at the most prolific Premier League striker in this way:
Sergio Aguero is in a small band of freak players in the top leagues who smash the concept of expected goals (xG) as if they were sent up from hell by ESPN’s Craig Burley. Over the last two and a half seasons he’s scored 11 more (xG 50, goals 61) than you’d expect the average Premier League shooter to from the set of shots he’s had.
Romelu Lukaku is a striker I guess most would put down as a player getting by on being a ‘top’ goalscorer when his all round game’s not that good. Does Rom smash up xG? Nope. Here’s him over the last two and a half years:
Keeping up with xG (especially at this volume of shots) over time is only something that those with a genuine eye for goal do. When you consider Lukaku’s goalscoring is average over time you realise that being average over time is HARD.
Ok, so what about Dele Alli, then? Take a butcher’s since he joined Spurs:
As you can see from Dele’s distribution above, there’s a small chance he could have even scored 26 in his Prem career so far.
When something tells you something is ‘nailed on’ in football, then switch the radio or TV off, put your paper or phone down, or simply walk away. They’re talking shite.
Follow me on twitter @footballfactman