The Best Shot Suppressing Centre Backs in the Scottish Premiership
written by @TheGersReport
Back in the summer of 2017, I introduced a set of shot suppression stats that I had compiled for the 2016-17 English Premier League season. The work was inspired by a similar project done by Matt Cane in which he used shot location data to analyze individual defensive play in the NHL. Cane, who was just hired by the New Jersey Devils to be their Director of Hockey Analytics, helped me develop my own variation of his work as a means of quantifying shot suppression for center backs.
The rating I developed comes from a pretty simple approach. Let’s look at which sides of the pitch that shots are coming from.
I went through the shot maps from each match in the Scottish Premiership this season & tracked where shots were being generated. I split the attacking third in half & recorded which half of the pitch the shot was taken. I only included shots that originated from inside the box & those taken just outside the penalty area. For example, the shot taken by #31 counts here, but those taken by #s 35 & 8 do not.
So in this example, there were a total of six shots counted, two from the right side of the attack & four from the left side. These shots are displayed from the point of view of the attacking player, when attributing the shots to the two defenders, the left-sided center back saw two shots come in their area that I label as his ‘zone of influence’ & four came in the vicinity of the right center backs’s main zone of influence.
As the data adds up you can see what percentage of shots came from either side of the pitch. Now, I am the first to admit that this isn’t perfect. Football is a fluid sport. Sometimes a left sided center back is caught up on the other side supporting his partner. Often a breakdown occurs elsewhere that the center back has no control over.
But, over hundreds & thousands of minutes some definitive trends occur…these trends should be learned from & can bring some real insight to the effectiveness of the different center backs in the league.
Basically, for a stat like this I think you should hone in on the outliers to see why their numbers are so extreme in a good (or bad way).
Over 7,000 shots were accounted for & with that data I developed a rating system that shows how well center backs were at suppressing shots in relation to their defensive partner. I will explain how this rating works, but first let’s look at some of those outliers I mentioned.
Below are the top rated center backs when it come to shot suppression (I used 1,000 minutes played as the minimum).
The biggest outlier in this data set was clearly 21-year old Filip Benković who played for Celtic on loan from Leicester City this past season. Let’s use his example to show how his rating is determined.
Only 35% of the shots that Celtic faced came in Benokovic’s zone of influence as a left sided center back
Since I want to develop a rating that was positive in nature, I then flipped that view to see what percentage of shots are coming from his partner’s area. In this case, it’s 65%.
For all the shots taken in the league this season, 49.5% come from the left side (against the right defender). As it pertains to Benkovic’s partners, 65.4% came in their area.
When you subtract 49.5 from 65.4 you get the Relative Shot Suppression rating of +0.16
That rating is attributed to Benković because the vast majority of shots were coming in the zone of influence of his partner. He is getting credit for the absence of shots in his zone.
Again, this is not perfect & there may be defenders whose ratings are inflated because they play with bad partners. But, for Benkovic - his partners included the likes of Kristoffer Ajer, Dedryck Boyata & Jozo Simunovic. Benkovic’s rating isn’t so high because his partners are bad, rather here was a defender who really was that good at making sure shots weren’t coming from his main zone of influence.
This is a player who is a £10 million rated center back. We don’t know why his shot suppression rating is so good, all we know that it is nearly three times better than the next guy on the list. Now that this outlier has been flagged, the next step would be for a performance analyst to assess what it is that Benkovic is doing to prevent shots from occurring in his defensive zone.
Later in this post, I will share the rating breakdowns for each Scottish Premiership team to get a sense of why players like Connor Goldson & Christophe Berra are rated so high & while their partners….are not.
Let’s take a look at another shot suppression rating that factors in which strips away low quality shots & only looks at high percentage shots, or Scoring Chances.
Long time followers of my work will know that I like to root a lot of my analysis in the creation of Scoring Chances. Now, let’s flip that & see who is the best at limiting Scoring Chances.
Kicked shots from this shaded area, along with headed shots from the six-yard box, are much more likely to score then other shots. These kinds of shots tend to have a 20% or higher Conversion Rate, while headed shots from the heart of the box (but not the six yard box) tend to only score around 9-10% of the time. Kicked shots from inside the box, but on the edges (non-shaded area) tend to have a similar 9-10% Conversion Rate. Shots outside the box typically have a 3-5% chance of scoring.
The center backs below had the best Relative Scoring Chance Suppression Ratings in the league last season & were the best at limiting these high percentage chances.
Alfie Jones is a 21-year old defender who spent a few months on loan with St. Mirren before returning to Southampton in January. He had a positive Relative Shot Suppression Rating (+0.02), while being pretty damn elite with his +0.10 Relative Scoring Chance Suppression Rating. He played on a bad team that gave up a lot of high percentage chances - St. Mirren allowed 2.49 Scoring Chances per 90 minutes that Jones played. For context, Hibs allowed 1.83 per 90 minutes that Efe Ambrose played.
Despite playing for an inferior team, only 37% of the Scoring Chances that St. Mirren allowed while Jones was on the pitch came from his main zone of influence. Teams were creating a lot of high quality chances against St. Mirren but for the most part they did not come from Jones side of the defence.
Again this is where data can become an entry point for further analysis. Jones is not a highly touted prospect like Benkovic, but went into a bad team & clearly was the best defender that they had. It may be smart for another Premiership club to go back & analyze his performances to see if they feel like he may be worth a short-term loan deal.
Team-by-team Breakdown (this time with a minimum of 800 minutes played)
The ratings for Celtic may be the most fluid simply due to the fact that their sample size of shots allowed is so low. For example, when Filip Benković was on the pitch Celtic allowed 3.58 shots per 90 minutes & teams only generated 1.10 Scoring Chances per 90 against them (remember the total shots only include the ones that I tracked from inside, & just outside, the penalty area). .
Again, given the sample size you almost need two seasons worth of data to make too many conclusive statements about outliers in the Celtic defence.
Simunovic was the only defender who had a positive rating in both shot & Scoring Chance suppression. The majority of shots came from his partner’s side (53%) & it was a rare event that a Scoring Chance was generated from Simonovic’ main zone of influence (76% came from his partner’s defensive area)
I wouldn’t overreact to Kristoffer Ajer’s numbers. His relative shot suppression was even to the league average. He spent most of his time as a left-sided center back & when he did 68% of the Scoring Chances came from his zone of influence. When he played on the right, only 33% of the Scoring Chances came from his defensive area.
This discrepancy is common across the league. While the shot rates were basically even as it pertains to whether they came from the left or right side of the attack… 53% of Scoring Chances came from the attacking team’s right side, while 47% came from the left side. Interestingly, the discrepancy was even greater the last time I ran these kinds of numbers. You could argue that when it comes to limiting high quality chances, being a left-sided center back is much more difficult then being positioned on the right (defending the attacks left’s side). This difference is included in the Relative Shot Creation Suppression Ratings & the results have been adjusted to account of the 6% difference league wide.
I decided to share this now, because it is a common belief that Ajer is one of the best center backs in the league & the data suggests that Celtic may be wise to lock him into that right sided role to get the most out of him defensively. When he played on the right side this season, even though it’s a much smaller sample size, he did a better job of limiting high percentage shots.
Connor Goldson is a player that I have written about quite often this season & often it was highlighting struggles he had as a ball playing center back. However, when you look at the league leaderboards for both shot & Scoring Chance suppression - there he is. The numbers verify the narrative that Goldson’s addition to Rangers backline has truly solidified the team defensively.
There has been a bit of a revolving door for other center back slot this season between Joe Worrall & Nikola Katic. Worrall took a back seat to Katic for the last month or so of the season & the team played its best football of the season in that time. It’s also the time in which the club settled on a midfield of Steven Davis, Glen Kamara, Ryan Jack & Scott Arfield.
Additionally, Steven Gerrard’s tactics were clearly modified whenever he had Jermain Defoe in the lineup.
Ok…just trying to soften the blow for what you’ll see next…
I teased this blog post by sharing the chart above on my Twitter feed…& it didn’t land all that well. Again, the team did play much better at the end of the season, but I wonder to what extent that comes down to the presence of Katic in the lineup or was having a solidified midfield of Davis, Kamara, Jack & Arfield more influential in the team’s overall play?
All I know is the following:
Katic spent 95% of his minutes playing as a left-sided center back & when he did…60% of the shots & 67% of the Scoring Chances came from his main zone of influence.
This does not mean that I think Katic is bad. What it does is, once again, bring up the belief that these kinds of objective facts give performance analysts something to really focus on when evaluating Katic’s play this season. How different were these numbers with Kamara & Davis playing in front of him? What impact did having the likes of Joe Flanagan & Andy Halliday as the defensive support from the left back position have on these results? Or is there something that Katic does/does not do in his defensive play that is leading to the discrepancy in shots coming from his main area of influence?
Stuart Findlay is among Scotland’s brightest defensive prospects & this has led to speculation of a move down south, along with a call-up to Steve Clarke’s first Scotland squad. The fact that he is among the league leaders in Relative Shot Suppression Ratings helps that list pass the sniff test.
Killie played most of this past season with a center back pairing of Findlay on the left & Kirk Broadfoot on the right. We established earlier that playing as a left sided center back is statistically more challenging when it comes to allowing Scoring Chances. Findlay is still a young player & this could be an area of improvement for him. Are there adjustments he can make to his defensive game to get even better?
When healthy, Scott McKenna was the mainstay in Aberdeen’s backline while Andrew Considine & Michael Devlin tended to split extended runs as McKenna’s center back partner. The numbers suggest that one of them was clearly the better fit for the Dons’ defence.
There is a real consistency in Devlin’s numbers:
46% of shots allowed came from his main zone of influence
44% of the Scoring Chances
44% of the goals allowed
When it comes to McKenna, there really shouldn’t be too much concern with his -0.02 Relative Shot Suppression Rating…52% of the shots came from from his zone of influence which isn’t much more than a 50/50 split.
When assessing McKenna, it’s that +0.04 Relative Scoring Chance Rating that highlights his defensive abilities. League wide, 53% of all Scoring Chances came from the right side of attack. When McKenna played as a left-sided center back (which he did 93% of the time), only 46% of the Scoring Chances came from that right side of attack. That’s what has driven up his rating here.
Even though I’m not in the loop of how the Hibernian Twitterverse views the different players on their team…I do get the sense that one who splits opinions the most is Paul Hanlon. However, his numbers here actually look pretty positive.
Hanlon was one of the better center backs at suppressing Scoring Chances this past season. Even though there was a 50/50 split between him & his center backs - it’s the fact he plays as the left sided defender that gives him the boost.
Before bolting for Derby County, Efe Ambrose was an elite defender at limiting dangerous chances. Shots were still coming from his area but he forced them to the outside at a high rate…49% of all shots came from his zone of influence but only 39% of the Scoring Chances.
The narrative this season was that 34-year old Christophe Berra may have taken that turn in his career in which he was officially “over the hill.” That common view probably comes from the fact that when he played as the left-sided center back, the majority of goals (55%) came from his main zone of influence.
Interesting side-note, when he was the center of a back three…14% of the goals against the left side of Hearts defence & 86% against the right side.
Goals create narratives. But the reality is if you simply look at shot suppression & quality chance suppression…Christophe Berra was still among the very best center backs in the league.
These results probably will surprise most people, especially given the reputation John Souttar has developed as one of Scotland’s best young defensive prospects. So I will simply present the facts & let them do the talking (& keep in mind that Berra plays the more difficult role as the left center back):
44% of the shots came from Berra’s main zone of influence, 51% of the shots came from Souttar’s
46% of the Scoring Chances came from Berra’s area, 50% from Souttar’s
The numbers aren’t terrible for Souttar…but they’re not as good as a bunch of other young center backs highlighted in this post (Findlay, Kerr, McKenna, etc).
Also, I think it’s safe to make the argument that 21-year old Jimmy Dunne may have been the best defensive player in the Premiership before his loan deal switched from Hearts to Sunderland.
Jason Kerr has come to the fore as one of the best young center backs in Scotland & that was accentuated by the fact he was linked to move to the English Championship this past January.
This is a case in which the numbers support the narrative. The majority of action on St. Johnstone’s goal was coming from areas that Kerr was not the most responsible for. The liabilities of Joe Shaughnessy on defence was actually something I first brought up back in October & that continued with 61% of the goals against coming from his main zone of influence.
A groin injury kept Charles Dunne out of the lineup for the first few months of the season. This was a worst case scenario for Motherwell given that they had also had lost Cedric Kipre to a move down to Wigan Athletic. When Dunne returned….well, the numbers suggest that he was among the least effective center backs in the league.
Dunne’s numbers are cushioned a little bit given he plays as a left sided defender but the fact remains that the majority of chances are coming from his zone of influence — 54% of the shots, 60% of the Scoring Chances & 55% of the goals.
It should also be noted that none of the main center backs for Motherwell has a positive Relative Shot Suppression Rating. It also should be noted that the club has already looked to upgrade with the signing of Livingston’s Declan Gallagher, who will be one of two Livi defenders leaving this summer.
It’s still a little mind blowing that Rangers let Craig Halkett go to Livingston on a free transfer back in 2016. At the time he was only 22-years old & now two years on has leveraged his time with Livi into a three-year contract with Hearts. If he continues on the career trajectory he has established with Livingston, you would think that the Jambos will cash in on a decent transfer fee in the next year of two.
It was already established at the beginning of this (very long) post that Halkett is one of the best shot suppressors in the league. He played most of this season as the central defender in a back three. Given he is naturally right footed, I have to attribute the right side of the defence as his main zone of influence. Again, this rating system is far from perfect.
Interestingly, another player who is charged with defending the right side is Motherwell’s aforementioned summer signing, Declan Gallagher. His ratings here aren’t great & one stat that truly sticks out is that when Gallagher played as a right sided defender (which was the vast majority of his minutes)…61% of the goals allowed came from his main zone of influence (to be fair, Halkett’s goals allowed rate is nearly identical).
Maybe Alan Lithgow is the true hero here…?
Matthew Kilgallon is a 35-year old journeyman defender who came into a bad Hamilton side & despite playing in a porous backline, the numbers suggest he may be the kind of savvy veteran that a mid-table Premiership club could depend on to solidify their defence.
Kilgallon had the fourth best Relative Shot Suppression Rate in the league with only 45% of the shots coming from his main zone of influence. His +0.03 Relative Scoring Chance Suppression Rate was just below that elite group highlighted in the beginning of this post, which was driven by the fact he played mostly as a left sided defender.
It should be noted that Shaun Want just missed the 800 minute minimum to be included in the fancy graph above. The 22-year old had a Relative Shot Suppression Rating of -0.07 & a Relative Scoring Chance Suppression Rating of -0.09.
Both rates are near among the very worst in the league.
The impressive numbers for Alfie Jones has already been mentioned earlier, but quietly the stats for 22-year old Jack Baird suggest that St. Mirren may have a capable, young center back that has flown under the radar.
Man, I forgot how good Alfie Jones numbers were.
Seriously, he’s rated as a £89,000 player by Transfermarkt & is only 21-years old. Southampton won’t be looking to sell an asset signed through 2021 but he should be getting looks from clubs for another loan spell. It won’t happen…but I wouldn’t mind seeing Rangers making that kind of move for him.
Back to Baird, the numbers aren’t spectacular but only 47% of the shots originated from his zone of influence. Another stat of note that’s interesting is that - of the 40 goals allowed while he was on the pitch…only 15 came from his main zone of influence (38%).
If a team like Livingston had the budget to make this kind of move…Baird may be someone that they could target to replenish their depth squad on defence.
I gave up trying to figure out Dundee a long time ago…
Stats are courtesy of data provided by Ortec Sports.
Sorry I spell center the way I do…it’s an Americanism I can’t break.
I don’t know the repeatability of this stat, because I haven’t had the chance to test it out. It’s a time consuming set of data to track. I do know that having Nicolas Ottamendi, Virgl van Dijk, César Azpilicueta & David Luiz top the Relative Shot Suppression Ratings back in 2016-17 was the kind of sniff test that made me feel good about continuing with this work.
Again, I do not look at this (or any defensive stat) as a truly definitive measure of what makes a good defender…rather, I see it as an entry point to learn more about the performance of a player or even a defensive system.
I can’t thank Matt Cane enough for being an initial though partner & sounding board when I first was working through this statistic back in 2017. It turned into a series of blog posts that ultimately was my platform to share a process that was both enriching & sleeplessly frustrating…I know…get a life, nerd.
I think even more can be learned from this dataset…so here is the link to the spreadsheet. Please note, sorting the data will throw the whole thing for a loop…so be forewarned.
This was written under the influence of The Warlocks, Amyl & the Sniffers, Nots, Spiritualized & French Vanilla.