An idea seems to exist with football fans on social media that Mohamed Salah is a poor finisher. This statement feels somewhat counter-intuitive for a player who has won the Golden Boot award in each of his first two full seasons in the Premier League. Especially given that he holds the Premier League record for the most goals in a single season (34) and the most games scored in during a single season (24).
However, those who hold this opinion of the Egyptian International come armed with stats. Their ‘fact’ proven with numbers seems to be Salah missing more big chances than any other player since signing for Liverpool (40).
Here is an undeniable truth: Salah has missed more big chances than any other player in the Premier League in the past three seasons. However, that isn’t what we were trying to measure, and trying to say this accurately measures finishing ability is a stretch that would make even Elastigirl wince.
The more times you do something, the more you will fail. If you have never played basketball, then you have probably never missed a free-throw. So, if you then started practicing free-throws every day, the number you are missing will steadily rise. Every single day, you will cumulatively miss more free-throws than the previous day. Does that mean you are getting progressively worse at free-throws? No, of course not. Like any skill, the more you are practising it, the better you will become at it.
If this argument is accurate, then you would expect the players who get the most ‘Big Chances’ are also the ones who score the most goals.
There is a clear correlation here between the top goal-scorers and the number of big chances they are missing. Therefore, if poor finishers miss the most ‘Big Chances’ – then we would have to believe that teams are picking their worst finishers as strikers to get the most chances. Again, this seems counter-intuitive.
When you look outside the Premier League, this correlation remains true. In Germany, Lewandowski has missed the most ‘Big Chances’ (68). In France, it was Mbappé (46). In Spain, we find Suarez (56) and Messi (40). So, either Lewandowski, Mbappé, Suarez, and Messi are worse finishers than Salah, or this is a terrible and likely contrary measure of finishing ability.
The problem with focusing solely on ‘Big Chances’ in this discussion so far is it ignores the vast majority of shots a player takes. So far in the top 5 leagues this season, there have been 38,715 non-penalty shots taken. Of those, only 4,658 are big chances; just 12% of total non-penalty shots.
The best finishers are often defined by the ability to turn small goal-scoring chances into goals. To get a shot off when there doesn’t appear to be space to do so. To find the corner of the net when the goalkeeper and defence seem to have every angle covered.
Nobody has scored more goals in Serie A over the past three seasons than Ciro Immobile. He is on his way to claiming his second Capocannoniere in three years, leading the scoring charts with 29 ahead of Ronaldo’s 26 goals. However, just 28% of his non-penalty goals have come from big chances.
In La Liga, we see likewise with perhaps the greatest player of all time, Lionel Messi. Just 35% of his non-penalty goals come from big chances.
That isn’t true of everyone, of course; Lewandowski has claimed 83% of his non-penalty goals from big chances. The point remains: we cannot have big chance myopia. We need to look at all the chances a forward is taking on board.
Therefore, perhaps the best way to isolate finishing ability is to look at how a player is performing against xG. Expected Goals (xG for short) is the probability of a player scoring from any shot.
For example, a penalty has an xG of around 0.76. That is to say, 76% of penalty shots result in goals irrespective of the shot taker, goalkeeper, etc. Likewise, Fabinho’s thunderous strike against Crystal Palace had an xG of 0.019. As in, 1.9% of shots from where Fabinho took his will result in a goal.
So, a player who is scoring 30 goals from an xG of 20, is performing at 150% of their xG. If another player scored 10 goals from an xG of 20, this would be a performance of just 50%.
Looking once again at the top 10 goal-scorers over the last three seasons, we can see how each has performed against xG. Firmino and Sterling are the only two high-volume goal-scorers who appear as objectively ‘poor’ finishers. As in, they both performed below what xG says they should. That would suggest they are better at getting into or creating for themselves goal-scoring chances than they are at clinically finishing the chances that do come their way.
Liverpool duo Sadio Mané and Mohamed Salah are both excellent finishers performing at around 110% of what xG expects of them. It doesn’t mean they don’t miss chances they should score; literally, every player will have glaring misses over their career. It means that, based on the probability of scoring the chances they had, they scored 10% more goals than they should have.
The final test for any goal-scoring metric is to make sure it passes the ‘Messi-test’. Does Lionel Messi appear like a good finisher or bad finisher with this metric? Well, Messi has scored 81 non-penalty goals from an xG of 63.06 in the last three seasons. It means he is over-performing his xG by 128.5%, better than all the high-volume goal-scorers in the Premier League.
I guess people can believe in a metric that shows all the worst finishers in the world are also the top goal-scorers to criticise Salah. Or, if their cognitive dissonance allows them, they can trust a metric that tells them Messi is the best finisher in the world, and the best goal-scorers in the leagues are also the best finishers – including Salah.