For obvious reasons, there’s been a great deal of discussion lately about Simon Mignolet’s performances this season. Some of the most widely shared assessments have focused on the total number of shots that Mignolet has faced. While these are helpful to a point, a richer appraisal of his displays can be achieved by focusing instead on the quality of those shots.
Thank you to Warren Pegg for this excellent guest piece!
It’s clearly unfair to berate a goalkeeper for failing to save a shot that was blocked before it even made it into the penalty area – or one that sailed 30 feet over the crossbar. Similarly, keepers shouldn’t receive too much praise for saving a shot taken from 40 yards out or from an extremely acute angle. All shots are not equal.
Please note that the goalkeeper stats below are sourced from PL games up to and including match-day 20, so they don’t take into account Alex McCarthy coming in for Fraser Forster at Southampton, or Karius’ starts for us against Leicester, Man City and Swansea.
Keepers who played less than 200 minutes in those 20 games have also been excluded, as the sample size is so small, meaning that Karius, Myhill (West Brom), Gazzaniga (Tottenham), Bravo (Man City) and Karnezis (Watford) are all omitted. Karius only faced a single shot on target (SoT) during this period, so it’s impossible to draw any meaningful conclusions from his two matches, except that he was well protected by our outfield players.
Before we look more closely at Liverpool’s stats, it’s worth reminding ourselves that in general terms, there’s nothing inherently bad about a team’s goalkeeper(s) not making many saves per game. This is underlined by looking at the sides in the top five European leagues with the highest and lowest numbers of saves p90.
We’re in very good company there. The group of teams with the highest saves p90 emphasises that, as with the majority of defensive actions, both good and bad players in bad teams will post high numbers.
Next, we’ll move on to some things that Liverpool as a team are very good at.
In Premier League terms, we’re exceptional when it comes to limiting our opponents’ attempts on goal. And even if the comparison is broadened out to include all five of the top European leagues, only City and Napoli outperform us.
Similarly, during the first 20 league games of the season, on average our keepers only faced a shot on target every half-hour or so. That’s the third-best figure in the PL and very near to half the rate of some other sides in the league.
This is all very fine indeed, but there are some defensive aspects of the game in which we perform considerably less well.
The xG values above are an indication of the quality of the chances that Mignolet has come up against. By comparing the attempts on goal that he’s faced to very similar previous attempts taken in very similar situations, an assessment can be made as to how likely it was for those shots/headers to result in a goal.
And by this metric, the chances for opposing sides when playing against Mignolet this season have on average been of a higher quality than those faced by any other PL keeper during the same period. To a limited degree, you could make a case that Mignolet himself has occasionally contributed to this. The most glaring examples are the ill-advised sprint out of his goal for Kane’s first against Spurs, and him flapping at crosses for Kane’s second in the same game and Okazaki’s goal for Leicester earlier in the season.
But it’s also clear that our outfield players are much more responsible than our goalkeepers for the high average quality of the chances that we concede. In a similar vein, of keepers who’ve played regularly in the PL this season, only Hennessey at Palace has faced a greater likelihood that the shots against him are on target. The proportion of our opponents’ shots that we’ve blocked has also been well below average.
While all of that mitigates against criticism of Mignolet, there’s still plenty to indicate that his performances haven’t exactly been at an elite level overall.
By comparing the xG value of the shots that a goalkeeper has faced with the actual number of goals that said keeper has conceded, we have an indication of how they’ve performed in comparison to other keepers who’ve faced similar chances in the past.
Above, we can see that Mignolet has conceded around three goals more than he would have been expected to. In percentage terms, he’s let in 14% more goals than keepers have in the recent past from similar chances, while David de Gea and Thibault Courtois have conceded around one-third and 10% fewer respectively.
It also appears that Mignolet genuinely has been more calamity-prone than the majority of his peers. Very few keepers have committed more defensive errors or conceded goals more frequently from the SoTs that they’ve faced. Obviously, the average xG values of those SoTs would be very useful here, but I haven’t had the time to calculate those figures yet.
Going back to the issue of the number of goals that we’ve conceded being greater than the xG value of the shots that we’ve faced, it’s worth noting that the disparity between the two has decreased markedly since Klopp’s arrival.
In recent seasons, we were among the worst performers in this area. Now, we’re somewhere in the middle. That isn’t great, clearly, but it’s an improvement.
Finally, let’s look more closely at the goals that we conceded in those first 20 league matches.
The vast majority of those goals were scored from inside the “danger zone” that runs roughly from the sides of the six-yard box up to the edges of the penalty area. Only three of the goals that Mignolet has conceded have come from outside that zone.
Most glaring among them was of course the Granit Xhaka howler against Arsenal. Xhaka has taken 37 shots from outside the area in the league this season – the third-highest in the PL – but that’s the only one to result in a goal.
The other occasion that Mignolet was beaten from outside the area was for Sane’s second goal against City. While the ball didn’t go right into the top corner, it was close and was struck well. The third goal from outside the “danger zone” was Willian’s mishit equaliser for Chelsea. It seems unfair to blame the goalkeeper for such a freak goal, although some have nonetheless managed to do so.
With regards to the placement of the goals that Mignolet has conceded, the nine in and around the centre of the goal-frame stand out.
Four of these were uncontested shots/headers from inside the six-yard box, one was a penalty and another was a one-on-one. Again, it seems hard to blame a keeper for conceding from such chances.
For the remaining three goals, though, it’s just as difficult to make a case that Mignolet wasn’t at fault. During the two aforementioned Kane goals, poor decisions by Mignolet had caused him to leave the centre of his goal vacant. And then came the Xhaka goal, which needs no further explanation.
All of this serves to underline the fact that defensively, we have two separate issues to address. One is the performance of whoever’s between the sticks. The other is that the chances they face are of an unusually high quality and are far more likely to result in a shot on target – and far less likely to be blocked – than is the norm. And it isn’t so easy to see how an improvement in the former will necessarily have too much bearing on the latter.
*Stats from WhoScored, Squawka, SofaScore, Understat.