Liverpool have completed the signing of Loris Karius, a goalkeeper who plied his trade in the Bundesliga for Mainz. The first statistical tweet I saw regarding him came from Sam Jackson (Twitter) last week. You may or may not be familiar with Sam, but I saw him give an excellent presentation on goalkeepers at this year’s Opta Pro Forum (which you can watch here), and this was his initial reaction to the news:
Oh. That’s not good. You can imagine Tony Pulis and Sam Allardyce licking their lips at this news (sorry for the horrible image there). If Karius is struggling with crosses in a league where teams average 13.7 crosses per game (and no team averages more than 19 per match) and is coming to a league where the average is 20.9 per team per game (and only two teams average fewer than 19 per match) then he is going to be severely tested in one potential area of weakness in the Premier League.
So far, so Mignolet. The Belgian trades on his ‘decent shot stopper’ reputation, but how does Karius compare? Fear not, Reds fans, this is where the good news starts.
I’ve been collating Premier League shots on target data this season with a view to building a very simple expected goals model. I need to write a lengthy explanatory article when I have more time, so for now you’ll have to roll with my findings, but essentially I’ve broken shots down into six categories, and by using the average conversion for each category I can calculate expected goals numbers. It’s far from the most accurate system out there as I will openly admit, but it is simple and easy to maintain, which suits (and describes?!) me perfectly.
I don’t have a breakdown by goalkeeper for the Premier League, but here is how Karius’ performance for the last three seasons, and in total, compared to clubs in the top flight of English football in 2015/16. I don’t have expected goal figures for the Bundesliga, so I had to apply the Premier League numbers to the shots Karius faced. The table is sorted by how much Karius or the teams over or under performed their expected goals tally.
Holy cow. This boy can really stop shots, no? Each of his last three seasons has been better than any team in England this season, using my new system. The figures did make me wonder if the conversion rates for my chance categories are different in Germany, so I excluded penalties and other clear-cut chances (which are defined as “A situation where a player should reasonably be expected to score usually in a one-on-one scenario or from very close range”) from the above figures and on the regulation shots Karius has over-performed by 26% across his career!
This just didn’t seem right to me, so as I don’t have time to figure out expected goal values for the whole Bundesliga, I figured out the average shots on target conversion rate in Germany (28.8%) for this season and compared it to England (30.5%) and it showed that fewer goals are scored. I factored down his total figure using the lower finishing rate and that lead to an over-performance across his career of 14.2%, which seems far more reasonable. But whatever way you slice it, he appears to be a very capable shot stopper. Out of interest, here is the top ten from the above table, but using these amended values for Karius.
This is a classic example of the kind of tweets that the superpowers of football stats churn out; they initially seem interesting, but then you realise you have further questions that you can’t answer. Karius made the most saves from shots taken outside the box, but did he also face the most shots from there too?
I can’t answer my own question there (gee thanks, WhoScored), but I can look at how he has fared with shots from different locations.
We can see that his strongest area for performance across his career has been in the wide areas of the penalty area (which I define as the areas beyond the width of the six yard box). When you watch the below highlights package this finding makes some sense to me, as much as I’m no expert, as there are examples where he seems quick to race forward and close down space for attackers, which makes scoring against him from wide areas nigh on impossible.
I don’t tend to bother assessing passing stats for ‘keepers, as to my mind it’s always down to the team that they play for and the manager’s tactics. Few people would believe that Mignolet had the best passing accuracy of any goalkeeper in the Premier League in 2013/14, but he did. He also had one of the lowest percentages of passes hit long that year too though, so of course his accuracy percentage would be high.
There was one element of distribution that caught my eye though (I couldn’t ignore it completely!). Squawka include method and distance of distribution, and one interesting thing I spotted when looking at Karius and Mignolet was the difference when it comes to throwing the ball out.
One of the many things that Mignolet does that riles Kopites is his tendency to claim the ball, run to the edge of his area, and then do nothing as his teammates race up field. The stats I found can’t prove that Karius doesn’t do the exact same thing, but I thought it was interesting that in 2015/16 he threw the ball out more often (170 times in 34 games, compared to 130 in the same number of matches for Mignolet) and further on average too (26m vs 23.24m).
Only three teams across Europe’s big five leagues averaged more shots per game on the counter attack than Mainz (though we have to bear in mind that most of the top teams for this are from Germany, so take this with a pinch of salt). Perhaps Karius started a fair few of these counters with accurate long throws? It’s just a theory, and anyone who has watched Mainz regularly would know the answer to this instantly, but it might be worth keeping an eye on next season.
The final area to ponder with a goalkeeper (when using stats at least) is defensive errors leading to opposition shots. Simon Mignolet made the joint-most in the Premier League this season (six) so how does Karius compare?
The good news is that thanks to fellow Liverpool statto Dan Kennett (Twitter), we can see that the former Mainz man has performed well on this front across his whole career:
8353 minutes, 10 errors, every 835 minutes
All LFC GK since 2011/12
18008 minutes, 32 errors, every 563 minutes
All EPL GK since 2011/12
360,861 minutes, 483 errors, every 747 minutes
It’s unrealistic to expect your goalkeeper to make no errors at all, as any mistake they make almost inevitably results in a shot, if not a goal, so it’s encouraging to see that Karius has been above Premier League average, and a fair distance above Liverpool’s collective goalkeepers in the last five seasons when it comes to making costly errors.
At just £4.7m, it seems like a no-lose transfer financially, and the numbers suggest that the Reds may have potentially solved a problem position for years to come. Though Karius may wish to look away now from this clip: Roberto Firmino scoring against him in March 2014. Welcome to Liverpool, Loris.