Where analysis starts to meet tactics: Finishing Quality

It’s not just our goal at 11tegen11 over the summer period to feed you with analytics pieces, although at the present rate you may start thinking otherwise. The aim is to provide more detail in analytics and ultimately to remove the barrier between analytics and tactics.

Long term readers will know that 11tegen11 started out, back in 2010, as a pure tactics oriented blog, but since then, slowly the analytics part has crept in. Pure tactical analysis has become a rare commodity here, after analytics took over. The main reason behind this, and I can safely say that now, is that tactical analytics is all hindsight bias.

Early this year, Richard Whitall put it very nicely in one of his State of Analytics columns

This is not to say that this kind of subjective interpretation of tactical trends, strengths and weaknesses is without value, but I do think it is subject to abuse. For example, it’s too often the case that some writers will imply a strong causal link between a certain, game-specific formation and a final outcome or set of outcomes.

These two sentences kind of bring together why I gave up writing tactical match reports. I missed the evidence to make my statements and basically, explaining tactics in the context of highly luck-driven outcomes felt like the abuse that I just quoted.

So, let’s move on and hope that analytics and tactics will soon merge. I firmly believe that trend has recently started, and it won’t stop soon. Analysts are nothing without tactical content, just as tactics are empty without empirical evidence to back it up.

This post was intended to tackle the issue of finishing quality, so let’s continue and do a little thought experiment. Try and answer this simple question…

What does it take to score a goal?

Simple, right? Creating a shooting opportunity and finding the back of the net. Correct.

In the previous posts, we’ve focused on the first step: creating shooting opportunities. Teams differ in two respects here: better teams create more shooting opportunities and they create better shooting opportunities. Both the number of shots created and the amount of ‘Expected Goals per Shot Created’ nicely correlate with the final league table.

But what’s up with step two? You may create less shooting opportunities, or shots with a lower ‘Expected Goals Scored’ number attached to it, as long as you make up for it by finishing more chances, you’ll be fine. Today’s post will identify Finishing Quality and come up with a simple parameter to judge teams or players by.

Remember that we’ve recently established a number for Expected Goals for each team. The number of Expected Goals is quite simple. Categorize each shot by strike zone and game state and look up the league average conversion rate for that shot. Add the total for all shots, and here we are, a total number of Expected Goals Scored.

We’re now just one step away from establishing Finishing Quality and that requires a comparison with the actual number of goals scored. Score more than the average Eredivisie team does from your shots (same number, same strike zone, same game state) and you’re an above average team when it comes to Finishing Quality. The next graph ranks all teams by Finishing Quality, defined as the number of Actual Goals Scored divided by the number of Expected Goals Scored.

Ajax and PSV, unsurprisingly, come up as the best finishing teams in the league. Vitesse and Roda complete a quite distanced top-4. Heracles is somewhere behind them in 5th place, but certainly higher than their league ranking would suggest. At the back end, Groningen’s problem is uncovered without shame. Perhaps also surprising, Feyenoord, with a FQ of just 0.84.

We’ll take this one step further and provide split numbers per team per zone. In order to keep the number of graphs within limits, I’ve created this Tableau graph (scroll down) where you can flip through all of the teams and see their performances for yourself. I’ll go over all teams in brief, as I believe there are some very interesting numbers.

Pitch zones

ADO
Overall, ADO has slightly overachieved, with an FQ of 1.05. This has led to two more goals than expected, with the best number from Zone 2. Small differences between Expected and Actual Goals though, so hardly any different from the average Eredivisie team.

Ajax
With an FQ of 1.25 Ajax scores a quarter more than the average team would do from their shots. We can see this mainly comes down to long and medium distance shooting. Ajax’ FQ from Zone 3 (20/13 or 1.67) and Zone 4 (13/7 or 1.86) is downright impressive and indicates that they’re doing things quite right from distance.

AZ
Overall, with an FQ of 1.02 AZ are an average team when it comes to finishing. It’s just from distance (Zone 4) that they seems to overachieve a bit.

Feyenoord
Now here’s an interesting one. Third ranked Feyenoord proves to be one of the worst finishing teams of the Eredivisie, who’d have thought. The previous post had identified them as creating the best chances in the Eredivisie, but their FQ comes in at just 0.84. We can see that this problem arises in all four zones, but scoring only one goal from Zone 4, where five were expected is quite poor. They took a total of 159 shots from Zone 4, which deserves a more detailed examination in a later piece.

Groningen
The worst team when it comes to Finishing. Regular followers of the Eredivisie will probably know that already, but Groningen’s strikers really can find the back of the net. Their long distance performance is poor, but it’s Zone 2 that really catches the eye. Nine goals behind an expected tally of 32, that’s quite the difference between a firm top-6 spot and mid-table.

Heerenveen
Despite having a top striker in Finnbogason, Heerenveen scores below par with an overall FQ of 0.87. Their deficiencies are mainly all over the pitch, as they underscore in each zone apart from the true tap-ins of Zone 1.

Heracles
Here’s another remarkable chart. Heracles ranks 5th overall with an FQ of 1.12, and it’s mainly because of their performance in Zone 3. That’s the area just outside the box, or slightly off-central within the box. Another lead for further investigation is born.

N.E.C.
I can’t keep saying they’re all interesting, right? Overall, N.E.C. is poor at an FQ or 0.84, but their long distance efforts overachieve, while their performance from Zone 2 is dreadful. Saved for later.

NAC
Overall around average at an FQ of 1.05. The spread looks a bit like N.E.C., with an overachievement from distance and underachievement closer by. This time, though, the differences are small, and may be not even significant.

PEC Zwolle
With an overall FQ of 0.93, PEC Zwolle don’t surprise, but they graph point out their quality was mainly in Zone 2, where this newly promoted team outperformed the average Eredivisie level.

PSV
The top scorers of the Eredivisie with 99 non penalty goals have the second highest FQ, at 1.24, just behind Ajax. But in contrast to their title rivals, PSV overachieved from every zone.

RKC
Overall, RKC came in okay, at 0.97. The graph shows it’s their Zone 2 performance that did the trick, while the medium distance shots were the problem area.

Roda
The sign of a team with an excellent striker. Massive overachievement in Zone 2, while the rest is at par. Will be studied on player level, if only to satisfy Sanharib Malki’s fans.

Twente
With an FQ of 0.92, Twente underperformed. Mainly from distance it seems, although a team that held title ambitions prior to the season start should have a better close range strike force than this sub-par Eredivisie level.

Utrecht
Overachiever in the table with their 5th spot, Utrecht did not do so on the basis of Finishing Quality. At just 0.93 overall, they were on par from Zone 2, but disappointed from further out.

Vitesse
Much like the pattern at Roda, Vitesse overachieved (1.22) and mainly did so from Zone 2 and 3. Wilfried Bony, anyone? Stay tuned.

VVV
At 0.84 an unremarkable overall FQ, and the spread across the pitch is quite even.

Willem II
Their FQ is level with VVV at 0.84. The problem has not been to score from distance, but the close range has let them down.

3 thoughts on “Where analysis starts to meet tactics: Finishing Quality

  1. bart

    I just read that R. Koeman stated the following …

    “Statistics show that we (Feyenoord) were the team with the least number of goals scored from outside of the penalty area. We have to start taking a more varied tactical approach so that Pelle can be more efficient (i.e. net more goals).”

    hehe … you should mail him the link to this series of posts … not attempting to score a lot from outside the box (and thus not scoring many goals outside of the box) should be seen as a positive really, no? I know that the expected number of goals is 5 (compared to 1 scored) … but how about trying to get the ball INTO the box before shooting and thus raising the expected number of goals even more (thus doing what they have been doing, but then just better).

    Is Koeman just misinterpreting the data here? Trying to cover for weak finishing INSIDE the box (i.e. maybe Pelle really isn’t that good as Feyenoord hope to believe?)?

    ah well.

    Reply
  2. baaaaas

    Als het nieuwe seizoen begint en ik gebruik Finishing Quality om een enkele wedstrijd te voorspellen. Hoe bereken ik dat dan? De uitkomst graag in percentages met thuisteam winst, gelijkspel en uitteam winst.

    Reply

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