Expected goals can only tell us so much. When a player takes a shot from a certain location, with a certain number of players around him, xG can give us a general idea of how likely they are to score from that position. But what determines whether that shot is actually scored or not? One of these factors is ballstriking – how well a player can hit the football. A good ballstriker can elevate a lower quality change into an almost certain goal, whilst a poor ball striker will often find themselves on fail compilations on Twitter.
In isolation, this can be the difference between a goal and a miss. However, on a larger scale, this can be the difference between Champions League qualification and midtable irrelevance. If an entire squad lacks a good ball striker, games can be lost as shots aren’t scored. If ball striking doesn’t improve over the season, several points can be dropped, and ground can be lost. Inversely, prolonged spells of good ball striking can help a team exceed their xG consistently, helping them to shoot up the table. Examples of good ballstrikers can be found in the likes of Harry Kane and Marcus Rashford this season.
So how can we measure a player’s ballstriking ability? Post-shot xG tells us the likelihood that a shot will result in a goal, after taking the speed and trajectory of the shot into account. PSxG is predominantly used to evaluate goalkeeping performance. Post-shot xG for off-target shots is zero, so using it can help us see exactly how good a keeper is at shot-stopping. For a striker though, we can use this in comparison to regular, pre-shot xG to look at ballstriking ability. For a good player, post-shot xG will be greater than pre-shot xG – their strikes add quality to shooting chances.
Let’s look at how team in the Premier League have done over the course of the 2022/23 season in terms of ballstriking, to see if we can tell any stories from the stats.
Firstly, we can see a general trend across all teams: ballstriking after the World Cup declined. For many teams, after the Qatar World Cup, players tended to do worse with the shooting opportunities given. This may have come down to fatigue or the large break in the Premier League causing complacency. A team like Manchester United is a good example of this.
Before the World Cup, United’s players were able to make the most of their chances, hitting the ball well and seeing their PSxG exceed their xG. Just before the World Cup, their xG caught up. This can be taken more positively as the team creating better chances rather than negatively as the team getting worse at ballstriking. However, after the international tournament, xG continued to rise but PSxG started to fall. United were able to create better quality chances as the team began to click, but poor finishing began to creep into the side. Fans can point to the performances of Wout Weghorst and Anthony Martial as examples of this.
We can also see why certain sets of fans have been crying out for a “proper number 9”, or a better striker. Teams like Everton and Wolves consistently hit under their xG, contributing to their poor seasons. Injuries to Dominic Calvert-Lewin and a downturn in performances from Raúl Jiménez have been primary reasons for the two clubs finishing at the bottom of the goalscoring charts this season. In fact, both teams are also the bottom four for xG underperformance. Once we look at striking performance, we can begin to rule out things like good goalkeeping performances as reasons for xG underperformance.
How Ballstriking Cost Potter His Job
We can also look at a single club’s performances over the season to get an idea of what proportion of blame can be given to players over a manager. Let’s zoom in on Chelsea.
By looking at ballstriking as well as keeping performance against Chelsea this season, we can begin to suggest that maybe Graham Potter’s dismissal in April wasn’t entirely the manager’s fault. At the beginning of his tenure until the World Cup break, Chelsea’s ball striking was good if not spectacular, with pre and post shot xG being mostly equal.
However, during Potter’s first few games, goalkeepers were letting in more shots than they were expected to. For example, in Chelsea’s 2-1 victory over Crystal Palace, the team generated shots worth 1xG from chances worth 1.1xG – a minor 0.1xG loss – but managed to score twice – a whole 1 xG underperformance from ‘keeper Vicente Guaita. We can say that Chelsea “got lucky” here. After the World Cup, however, the luck stopped.
Poor ballstriking plagued Chelsea in 2023. Their 5-game rolling average suggests that the team generated shots worth less than the chances they created for the rest of Graham Potter’s time in charge. This continued for most of Frank Lampard’s interim spell as well. On top of this, goalkeeping performance against Chelsea largely improved – ‘keepers were letting in less than post shot xG would have expected them to.
It’s hard to blame a manager for a team’s poor ballstriking over the course of a season: they cannot physically get onto the pitch and shoot for them. But there are other factors that can lead to poor finishing outside of just players “not being good enough”. For example, confidence can have a large impact on a player’s ability to focus and concentrate when in a good shooting position. If a striker has been on a poor run of form, the pressure on them will begin to mount. This can lead to split-second hesitations when hitting the ball – and that can be the difference between a high-value and low-value shot.
Even finer details like pitch quality can affect ballstriking. It’s a lot harder to shoot well playing at Dingwall against Ross County than at Old Trafford against Manchester United. When managers like Jürgen Klopp or Xavi blame bad results on the grass, it isn’t complete nonsense (although most of the time, it’s a large exaggeration).
There were obvious reasons outside of ballstriking for Graham Potter’s sacking, of course. An inability to deal with a large squad lead to a lack of cohesion and tactical familiarity on the pitch, among other things. Whether a project manager like Potter should have taken a high-risk, low-security job at Chelsea is a good question to ask as well. But ballstriking will have played a significant role in the team’s season and is definitely something to address before the next one.
Chelsea’s story is just one example of how ballstriking plays a vital role in maximising a team’s output. For teams underperforming going forward, a good ballstriker who can generate high quality shots from good shooting positions is a must… unless you want to end up 12th in the Premier League next year.
