We’re now at the halfway point in the Championship and there’s a ton of data to interrogate to see how the transformation towards a side built on Michael O’Neill’s philosophy and personnel is performing in this eerily unique season.
A total 48 goals have been scored in Stoke City’s Championship matches, 26 coming the way of the Potters, but we can expand these data points to around 450 by looking at every successful or failed scoring opportunity through the lens of expected goals.
For those needing a quick refresher, expected goals or xG for short, looks at the circumstances that surround each attempt on goal, whether it was a shot or a header and where it was taken from to predict the likelihood that a goal is scored.
Stoke have been out-shot by the opposition. We’ve taken 145 shots and 66 headers in attempting to score and faced 191 and 47 respectively in return.
However, in keeping with the successful Stoke sides of the past, we have taken higher quality attempts, closer to the goal than our opponents and that has offset the shot deficit.
Stoke currently has an expected goals total of 21.9 created and 21.7 allowed. It’s pretty much a dead heat and here’s what each attempt looks like plotted on a pitch template.
Our keepers and defenders are again keeping our six-yard box relatively chance free and a special mention to Jordan Thompson’s rarity, a goal directly from a corner kick.
So how have we turned a near equivalence of location based expected goals into an actual record of 26 for and 22 against.
Firstly, all naturally occurring events, of which goal scoring can be included, are prone to randomness. Flip a fair coin 10 times and your expectation in the long run is five heads, but in a single run of flips it wouldn’t be a surprise to occasionally get six, seven or even 10, although the latter would be rare.
That’s part of the explanation, Stoke have enjoyed some positive variance or old fashion good luck.
Secondly, no model is perfect and data is patchy for such things as body orientation when taking a shot, defensive pressure applied to the player attempting to score and the difficult to pin down ability to finish in a clinical fashion.
We can investigate these incomplete variables by building a slightly different model, which includes everything that goes into a traditional xG model, but also uses information collected once the ball leaves the striker’s boot or forehead.
Did he connect well with the ball, which might imply less defensive pressure around the attacker. Was it well placed, hopefully out of the reach of the keeper and did it take a deflection, which may explain why an innocuous effort from distance evaded any attempt to make a save.
If we look at our new, post-shot xG model, we start to find where Stoke are making gains and encouragingly it’s on both sides of the ball.
Incorporate what happens after the ball is struck and the post shot expected goals created by Stoke increases to over 24, closer to the actual number of goals scored of 26 and defensively the value falls from 21.7 on the purely location based model, to 19.3.
On the attacking side of the ball, our shot placement from chances that are kicked towards goal improves the location based quality of the chance by around 10 per cent. We’re finding the corners well, with a little bit of added swerve, particularly from the currently injured Tyrese Campbell.
Headers have done even better, we’ve cleared out running lines with clever decoy runs, put in pin point crosses with pace and assembled a raft of excellent headers of the ball. Location based xG from headers has improved by over 30 per cent with our well-placed and powerful finishing.
Stoke’s two best players at improving the chances they’ve been given by making the opposing keeper work hard in 2020/21 are predictably, Campbell and Nick Powell.
Here’s the shot map for Stoke’s clinical finishing duo.
Defensively, we’ve been more of a mixed bag, but we are excelling in the hugely important area of degrading the quality of opposition shots at our goal.
We’ve given up a lot of kicked, rather than headed goal attempts, 85 per cent of our location based xG conceded has come from shots at goal. But we’ve done a tremendous job of nullifying those chances.
We’ve blocked 79 shots and have blocked the highest percentage of opposition goal attempts in the division. We also make our defensive presence felt to harry attackers or knock them off balance.
Only four teams in the Championship has done a better job reducing the quality of their opponents post-shot strikes at goal than Stoke.
There is room for improvement in some defensive areas.
We allow a league high percentage of our xG from 1 on 1 situations, but sample size is small and it’s a situation that will naturally improve.
And the rate at which our trio of keepers have made saves is below the league average once the quality and placement of the attempts they’ve faced are accounted for.
Fortunately, it’s usual to see a keeper’s shot stopping abilities oscillate between over and under performance in a limited number of matches and on the plus side cross claiming and distribution is well up to Championship levels.
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There’s no real alarm bells on the keeping front.
We possibly could upgrade when defending set pieces and corners, especially in the air. We may be forcing headers to be taken well away from our goal, but we could do better at pressurising the player making the header because they are currently finding the target a little too easily.
Typically, a side would score three headed goals against Stoke based on where the header originated, but they are hitting the target at a rate consistent with an expectation that nearly five headed goals might be scored.
It’s most likely statistical noise, but it could also be a failing we should easily be able to rectify.
Overall, a steady, but relentless transformation is taking place at the bet365, built on a solid underlying foundation. It’s a B+, with a definite transfer window agenda to do even better in the remainder of the season.